346
GLOSSARY
Glossary
Abnormal data Data that is of the wrong type (for example text
in a numeric field) or is outside the accepted range (for
example an exam mark percentage of 110).
Absolute reference Fixes a cell reference within a spreadsheet
so that when the formula is copied this cell reference never
changes.
Accuracy of information A measure of how free information is
from errors and mistakes. It often depends on the accuracy
of the original data which was collected.
Actor A group of actuators which combine collaboratively to
perform actions and make decisions, such as a robot.
Actual result Results obtained as a result of live testing.
Actuator A device used for controlling a device using the output
from a computer.
Adware There are two types where the malicious type is
generally regarded as being more of a nuisance than
anything else. It automatically generates advertisements on
a user’s computer.
Aggregated information When the personal details of a number
of people are combined to provide information without
individually identifying anybody.
Algorithm A list of well-defined instructions which can be
followed in order to produce a solution to a problem. Often
written in pseudocode, the instructions can be rewritten as a
computer program.
Alphanumeric A field type where any character is acceptable
input; sometimes called text.
Ambient temperature The temperature of the air surrounding
the device being used to measure the temperature.
Amplifier A part of a sound system that makes the sound louder
so that it can be easily heard.
AND Used to search with two (or more) conditions, where both
(or all) conditions must be true for the result to be true.
Anonymised information When the personal details of people
are stored without identifying anybody by name.
Anti-virus software Its function is to detect and remove viruses.
ASCII (American Standard Code for Information Interchange)
This is the standard set of codes (numbers) used by the
computer to identify each letter and symbol of the character
set (on the keyboard).
Asymmetric encryption Sometimes referred to as public-key
encryption, this uses two different keys, a public key used
to encrypt a message and a private key used to decrypt the
message.
ATM (active traffic management) Forms the basis of smart
motorways, using variable speed limits and controlling the
use of the (hard) shoulder for occasional use by moving
traffic.
ATM (automatic teller machine) A machine, operating as part
of a computer system, that dispenses cash and performs
other banking services when a customer inserts a bank card.
Atomic data Data that cannot be broken down into smaller
parts/greater detail.
Attachment A data type used within Microsoft Access to add one
or more files (including documents, presentations, images,
sound bites and so on) to the records in your database.
Authentication In IT terms, this is the process of verifying the
identity of a person or device, such as when using a user ID
and password when logging on to a computer system.
AutoNumber A data type used within Microsoft Access to
generate a unique integer value for each record created. If a
record is deleted its unique number is not reused.
AutoSum Function in Microsoft Excel that adds together the
contents of a number of cells.
AVERAGE Function in Microsoft Excel that calculates the mean
(average) of a list of numbers.
AVERAGEIF Function in Microsoft Excel that looks at the cells
within a given range and calculates the mean (average) from
those cells that meet a given condition.
AVERAGEIFS Function in Microsoft Excel that looks at the cells
within a given range and calculates the mean (average) from
those cells that meet a number of given conditions.
Back-end database A database that is accessed through an
application program rather than the database software.
It does not store database elements like queries, forms or
reports.
Back-up software Used to keep copies of files in case the
originals should get corrupted.
Backward chaining Used within an expert system and often
referred to as goal-driven because it starts with a goal or
set of goals that basically establish which rules are to be
followed.
Batch processing Occurs when several transactions are collected
over time and then processed all at once at a later time.
Behavioural-based detection A method of detecting viruses by
looking out for abnormal behaviour.
Biometric data Computer data relating to an individual’s
physical characteristics, including iris and retina
recognition, fingerprints, voice recognition, among others.
It uniquely identifies a user when used for accessing a
computer system.
Bit A shortened form of binary digit, this is the smallest unit of
measurement of computer data. It contains a single binary
value of 0 or 1.
Block A number of sectors on a hard disk smaller than a track.
Boolean A logical thought process developed by the English
mathematician and computer pioneer George Boole. See
Boolean operator.
Boolean operator The logical operators AND, OR and NOT,
which are used in searches (queries) within data handling
applications and return the values True or False.
Bot Short for internet robot, this performs tasks that are
normally undertaken by a human. When used to gather
information over the internet is called a web crawler.
Botnet A server that takes control of a network of infected
computers.
347
Glossary
Calibration Process of trying to ensure the accuracy of sensors.
Cascading style sheet A style sheet saved in CSS format with a
.css file extension. This allows the stylesheet to be attached
to each web page to define how to display the content layer
of a web page, without the page needing to contain the style
tags. If a number of cascading style sheets are used, the
multiple style definitions will cascade into one.
CASE…ENDCASE A type of condition used within an algorithm
that results in one of a number of alternative actions being
carried out.
Certificate authority (CA) Sometimes referred to as a
certification authority, this is an organisation that
issues digital certificates enabling transparent, trusted
transactions to take place.
CHAR Function in Microsoft Excel that returns the character
specified by a code number.
Check digit A validation check carried out on numeric data
consisting of long strings of digits. A calculation is
performed on the individual digits to produce a check digit.
After data input or transfer, the check digit is recalculated to
make sure it produces the original result.
Checksum A method of verification used to check that a whole
file has been transferred accurately, unlike parity checks
which check individual bytes.
Ciphertext Encrypted information produced as a result of
encryption performed on plaintext.
Client The name given to a computer or workstation that runs
programs and accesses data stored on a server when part of a
client–server network.
Client–server network A computer network which has a central
computer called a server to which many other computers
or workstations are connected. These computers or
workstations are called clients.
CODE Function in Microsoft Excel that returns the ASCII value of
a given character.
Codec A circuit capable of converting audio and video data
into a digital form and then compressing it for transmission
across a network.
Comma separated values A file format (.csv) used to hold
tabular data, such as from a spreadsheet or database table.
It stores it as a text-based file using commas (or semi-colons
in some locations) to separate the data items.
Command line interface (CLI) A means of interacting with a
computer using commands in the form of successive lines of
text.
Compiler Converts statements written in a high-level language
program into machine code for the computer to execute.
Compound key Multiple fields within a relational database table
that together contain unique data (no two records within
these combined fields can contain the same data). No field
within the compound key can contain a blank record.
Computer fraud Involves using a computer to take or alter
electronic data or to gain unlawful use of a computer or
system illegally to benefit financially.
Computer sabotage Making deliberate attacks which are
intended to cause computers or networks to cease to
function properly.
CONCATENATE Function in Microsoft Excel that joins several text
strings into one string.
Conditional branching The direction from one statement in an
algorithm to another part of the algorithm depending on the
result of a comparison being made.
Confidential data Data which is personal and possibly sensitive
which should not be revealed to other workers.
Consistency check Sometimes referred to as an integrity check,
this is a validation check which checks that data across two
fields is consistent.
Container A file format which holds data.
Contiguous data Data that is placed together and can be
selected in a single range.
Control system The use of microprocessors or computers
together with sensors to control a process.
Control total Similar to a hash total, in that the total value of
a numeric field is calculated; unlike hash totals they can be
useful when calculating the total amount in a profits field.
COUNT Function in Microsoft Excel that looks at the cells within
a given range and counts the number of cells that contain
numeric values.
COUNTA Function in Microsoft Excel that looks at the cells within
a given range and counts the number of non-blank (not
empty) cells.
COUNTIF Function in Microsoft Excel that looks at the cells
within a given range and counts the number of these cells
that meet a given condition.
COUNTIFS Function in Microsoft Excel that looks at the cells
within a given range and counts the number of these cells
that meet more than one given condition.
Cray XC40 Supercomputer Produced for the UK Meteorological
Office in 2017, with 172 000 processor cores.
.css See Cascading style sheet.
.csv See Comma separated values.
Currency The unit of money used by countries, for example
Egyptian pounds, Kenyan shillings, and rupees in India and
Pakistan.
Custom-written software Specially written software for a
particular task and developed for a specific company or
business.
Cyber-fraud The illegal use of the internet to deceive people in
order to obtain money, goods or services from them.
Data Often used as a shortened form of the term ‘raw data’, this
comprises characters, symbols, images, audio clips and video
clips, which on their own have no meaning.
Database A collection of data items and the links between them
which is organised and stored so that it can interrogated.
Database management system A complex software system used
to control, maintain and manage a database.
Database of facts Contains all the known facts of information
relating to a specific scenario which an expert system has
been created for.
Data compression See Zip.
Data logging Using an electronic device to record data over time
with a built-in sensor to monitor or measure physical variables.
Date and time A field type within Microsoft Access that is used
to store dates and times.
DAY Function in Microsoft Excel that returns a number between 1
and 31 as the day value from a given date.
348
GLOSSARY
DBMS See Database management system.
DC offset Unwanted DC output voltage which appears at the output
of an operational amplifier (op-amp) as well as the desired
signal. It is the average offset of a waveform from zero. It can
be a cause of clicks, distortion and loss of audio volume.
Decibel A unit used to measure the intensity of a sound (how
loud a sound is).
Decimal A data type used within numeric fields in Microsoft
Access to store the data in decimal format (including storing
numbers like 5.67).
Decryption key The key used to convert ciphertext back into
plaintext. In many systems the decryption key is the same as
the encryption key.
Defragmentation Process of organising the data on a disk to
reduce the number of blank sectors.
De-identification Removing items of personal data from a
record, such as an individual’s name.
Delete utility A type of utility software that deletes the
pointers telling the operating system where to find a file.
Device driver A small program that enables the operating
system and application software to communicate with a
hardware device.
Dialogue interface Allows a user to communicate with a
computer or device using their voice.
Digital certificate Used to verify the identity of a computer or
server and is issued by a certificate authority.
Digital divide A term used to describe the gap between those
people who are able to access modern technology and
information and those with restricted or no access.
Direct data Data that is collected for a specific purpose or task
and is to be used for that purpose and that purpose only.
Direct data access See Random access.
Direct data sources Sources that provide the data gatherer with
data that is first-hand.
Disk formatting The configuration of a storage medium ready
for initial use.
Disk surface The surface of a platter within a disk drive which
stores the data.
Double data entry Involves the entry of data twice; both
versions are compared by the computer and the person
entering the data is alerted by the computer to any
differences.
Double-entry verification A form of verification, see Double
data entry.
Duty of confidence The responsibility of an employee to the
company they work for and the customers whose personal
details they are dealing with to maintain the confidentiality
of the data.
Electoral register Often referred to as the electoral roll, this is an
example of an indirect data source. It is a list of adults who
are entitled to vote in an election, containing information
such as name, address, age and other personal details.
Electronic funds transfer (EFT) The electronic transfer of
money from one bank account to another using computer-
based systems.
Email account An arrangement with an ISP (see Internet service
provider) which allows users to send and receive emails using
an address provided by the ISP.
Encryption key Used for scrambling and unscrambling data; it is
used to convert plaintext into ciphertext and back again.
EXACT Function in Microsoft Excel that compares two strings/
cells and looks for an exact match including case.
Expected result The list of expected results of tests that are
going to be performed on a new system.
Expert system A computer-based system used to solve problems
usually of a diagnostic nature using databases of expert
knowledge.
Explanation system The part of an expert system which explains
the logical reasoning that the expert system has used to
come to its conclusions.
Extended ASCII An extended version of the ASCII system which
provides extra characters with codes from 128 to 255.
Extreme data A type of data used to test a system. Where data
must be within a certain range, extreme data is the data on
either boundary of the range.
False positive Happens when a virus detection algorithm is so
general that even though only a small number of suspicious
bytes are identified, the virus-free file is still considered to
be containing a virus.
Fault tolerance Ability of a mainframe to remain in use even
when one or more of its individual components fails.
Field A place used to hold a single data item within a database.
File A logically organised collection of records, usually where all
the records are organised so that they can be stored together
within a database.
File compression See Zip.
File copying A type of utility software used to create a new
copy of a file.
FIND Function in Microsoft Excel that returns the starting
position of one text string within another text string.
Firewall The hardware or software designed to prevent
unauthorised access to a computer network.
Flat-file database A database structure using a simple two-
dimensional table.
FLOPS A measure of how many floating-point operations per
second a supercomputer can perform.
Flowchart A data or program flowchart which represents an
algorithm in diagrammatic format.
Footer The area at the bottom of a document between the
bottom of the page and the bottom margin, sometimes used
to enter page numbers or the same text consistently over a
number of pages.
Foreign key The name given to a field in a table within a
relational database, which is linked by a relationship to a
primary key field in another table.
Formulae Sets of instructions used to perform a calculation in a
spreadsheet; can include cell references, numbers, mathematical
symbols and, in some cases, predefined functions.
Forward chaining Used within an expert system and often
referred to as data-driven, because the data entered into the
system determines which rules are selected and used.
Frame One still image that is part of a moving image.
General Data Protection Regulation (GDPR) The set of rules
used by the European Union to govern the protection of data.
349
Glossary
Gesture-based interface A user interface designed to interpret
human gestures and convert these into commands a
computer can understand.
.gif See GIF.
GIF (graphics interchange format) A format used to save still
or moving images. This is an efficient method of storing
images using a smaller file size, particularly where there are
large areas of solid colour. It is widely used in web pages.
Global digital divide The term used to describe the digital
divide between countries.
Goal Seek A feature in Microsoft Excel to give a required output
by repeatedly changing one item of input data using trial
and error until it finds the required output.
GPU (graphics processing unit) Similar to a computer’s CPU
but designed specifically for performing mathematical
calculations that are necessary for rendering all images on
the computer’s screen.
Graphical user interface (GUI) A user interface which uses
windows, icons, menus and pointers, to carry out commands.
Greenhouse Referred to as a glasshouse in some countries; used
in cooler countries to grow plants which normally only grow
in warmer climates.
Hacker A person who uses their programming skills to gain
unauthorised access to computers or computer networks.
Hash total A verification method where totals are calculated in
numeric fields in order to check data has been transferred
accurately, but unlike control totals, the results of the
calculations are usually meaningless, such as adding up a
number of student IDs.
Header The area at the top of a document between the top of
the page and the top margin, often used to enter the same
text consistently over a number of pages.
Heat maintenance Often referred to as heat management, this
is the controlling of heat produced by large computers to
manageable levels.
Heuristic-based detection A method of detecting viruses by
looking at source code to detect a pattern.
High-level formatting A type of disk formatting usually carried
out by a user.
HLOOKUP Function in Microsoft Excel that looks up data using
data organised in horizontal rows.
Hosts file A basic text file which contains the name and the IP
address corresponding to URLs.
HOUR Function in Microsoft Excel that returns a number between
0 and 23 as the number of hours shown on a 24-hour clock
from a given time.
.htm See HTML.
HTML (Hypertext Markup Language) A text-based language
used to create markup, so that web browser software can
display information in different ways.
HTTPS (Hypertext Transfer Protocol Secure) The protocol
whereby HTTP data is securely transferred over a network,
usually the internet.
Identity theft Illegally using another person’s name and personal
information in order to obtain credit, loans and state benefits.
IF Function in Microsoft Excel that looks at a given condition and
performs an operation if the condition is met, or a different
operation if the condition is not met.
IF…THEN…ELSE A comparison or condition made within an
algorithm which leads to another action or statement being
carried out or an alternative (ELSE).
INDEX Function in Microsoft Excel that returns a value or
reference of a cell, at the intersection of a given row and
column in a given range.
Indirect data Data that is obtained from a third party and used
for a purpose different to that for which it was originally
collected.
Indirect data sources Third-party sources that the data gatherer
can obtain data from. One such source is the electoral
register.
Industrial espionage Spying in order to discover the secrets of a
rival manufacturer or other industrial company.
Inference engine Performs the reasoning in an expert system
using a rules base and interrogates the database of facts.
Information Data which has been put in context or given a
meaning, usually after some form of processing, sometimes
by computer.
INPUT A statement used in pseudocode requiring a value to be
entered.
INT Function in Microsoft Excel that calculates the integer (whole
number) part of a number and ignores all digits after the
decimal point.
Integer A whole number with no decimal places.
Internet protocol (IP) Provides the protocol, or set of rules,
which governs how data is sent from one computer to
another on the internet. Each computer on the internet
has an IP address that uniquely identifies it from all other
computers on the internet.
Internet service provider (ISP) A company or organisation that
provides services for accessing and using the internet.
Interpreter Converts statements written in a high-level
language program into an intermediate form for the
computer to execute.
IPsec (internet protocol security) The authentication of
computers and encryption of data so as to provide secure
encrypted communication between two computers over
an IP network.
JPEG (joint photographic expert group) A format used to save
still images, originally named by the Joint Photographic
Expert Group. This is an efficient method of storing images
using a smaller file size and is widely used in web pages.
.jpg See JPEG.
Knowledge base A component of an expert system usually
comprising a database of facts and a rules base.
Knowledge base editor Software that allows a knowledge
engineer to edit the rules and facts within the knowledge
base of an expert system.
Knowledge engineer Person responsible for designing an expert
system after initially collecting information and data to do
with the system.
Label A value entered as text (or alphanumeric), often in
a spreadsheet cell or text control box displayed within
elements of a database package. This term is also used
within programming but is not within the scope of this book.
Lasso tool A tool used to select objects by holding down the
left mouse button and dragging the mouse around it, then
letting go.
350
GLOSSARY
LEFT Function in Microsoft Excel which returns a given number of
characters from the start of a text string.
LEN Function in Microsoft Excel which counts the number of
characters within a string.
Levels of access The sets of permissions or restrictions granted
to particular groups of users when accessing a computer
network. Some users will have access to parts of the system
that others do not have. It provides an effective part of
network security.
Limit check A validation check applied to one boundary in a
numeric range either at the upper or lower limit, unlike a
range check which tests both boundaries.
Linear progression The writing of algorithmic statements
or instructions in a sequence that uses the result of one
statement in subsequent statements.
Link editor See Linker.
Linker Also known as a link editor, this combines object files
or modules that have been created using a compiler into a
single executable file.
Lookup A generic term for looking up specified results from a
table of data.
LOOKUP Function in Microsoft Excel which looks up data using
the first row or the first column of a range of cells and
returns a relative value.
Loop A sequence of instructions within an algorithm or
flowchart which is repeated a certain number of times.
Lossless compression (images) This allows the original images
to be recreated with no loss of quality. (sound) This
preserves all the information from the original sound sample.
Lossy compression (images) This involves the loss of resolution
of parts of the image (often in parts of the image where it
will be least noticed). (sound) This does not preserve all the
information from the original sound sample and involves
some degradation of the signal.
LOWER Function in Microsoft Excel that returns a string as lower-
case characters.
Low-level formatting The basic form of disk formatting which
permanently erases data on a disk and is usually only carried
out by manufacturers.
Mainframe computer Used mainly by large organisations for bulk
data processing applications such as the census, industry
and consumer statistics, and transaction processing.
Malicious bot Behaves like a worm as it can replicate itself and
is designed to feed back to a server called a botnet.
Malware Short for malicious software, the overall term for
software which is a threat to computer security.
Massively parallel processing The type of parallel processing
employed by a supercomputer’s operating system making use
of the very large number of processor cores.
Master file A relatively permanent file that contains information
which is only periodically updated. An existing master file
is used together with a transaction file to produce a new
updated master file.
MATCH Function in Microsoft Excel that returns the relative
position of an item within an array, that matches a value
from a given location.
MAX Function in Microsoft Excel that calculates the maximum
value in a list of numbers.
Mean time between failures (MTBF) The average amount of time
a system is available between each time the system fails.
Measurement See Monitoring.
MEDIAN Function in Microsoft Excel that places a list of numbers
into sequential order and returns the middle number from
that list. If there are two middle numbers, the mean of those
two middle numbers is calculated and displayed.
Microprocessor A central processing unit on a single integrated
circuit chip.
MID Function in Microsoft Excel which returns, from a given
starting position, a given number of characters from the
middle of a text string.
MIN Function in Microsoft Excel that calculates the minimum
value in a list of numbers.
MINUTE Function in Microsoft Excel that returns a number
between 0 and 59 as the number of minutes shown on a clock
from a given time.
MIPS (millions of instructions per second) The measure of how
fast a mainframe’s CPU is dealing with computer program
instructions.
MODE Function in Microsoft Excel that extracts the most
frequently occurring number from a list.
Model A computer representation of a real-life process.
Modelling Creating a programmed simulation of a situation or
process that will allow data to be changed and examining the
effect that this has on other data. This is often done with a
spreadsheet and can be used to predict future trends.
Monitoring The observing and measuring of physical variables
using microprocessors or computers together with sensors.
MONTH Function in Microsoft Excel that returns a number
between 1 and 12 as the month value from a given date.
.mp3 See MPEG-3.
.mp4 See MPEG-4.
MPEG-3 (Moving Pictures Experts Group layer 3) A file format
used for storing audio files. It compresses the original audio
(sound) file to about 1/12 of the original file size while
keeping the original sound quality.
MPEG-4 (Moving Pictures Experts Group layer 4) A file format
(multimedia container) used for storing video files. It is also
used to store audio (the soundtrack to the video) and other
data like subtitles and still images.
Network policies Sets of rules that allow companies to choose
who is allowed to access their computer network. They
control an individual’s use of the network once they have
gained access.
Non-contiguous data Data that is not placed together (often in
a spreadsheet) and cannot be selected using a single range.
Normal data Data that is within an acceptable range and is
usual for the situation.
NOT Used to search with two (or more) conditions, where if the
condition is True the result is False and if the condition is
False the result is True.
Null string Often referred to as the null character, this has an
ASCII value of 0 and when sent to a printer causes no action
to be taken.
Number A value entered in numerical format; for example ‘5’ is
a number, whereas ‘five’ represents a number but is in text
format.
351
Glossary
Numeric Consisting of numbers: real, integer or fixed decimal.
Object linking and embedding (OLE) A Microsoft technology
that allows a file to be embedded and linked at the same
time to other documents/files and objects. Data that
is available in other applications can be accessed and
manipulated from the current document/file.
Off-the-shelf software Software which already exists and is
available straight away, ready for use.
OLE object A data type used within Microsoft Access to
store files created in other programs such as graphics,
spreadsheets, or documents.
OR Used to search with two (or more) conditions, where one
(ormore) of the conditions must be true for the result to
betrue.
Padlock An icon used by most websites. When closed it indicates
a secure connection has been established.
Parallel processing The way a mainframe operating system
splits a large task into several sub-tasks then recombines the
results once processed.
Parity bit The bit added to a byte when parity checks are used.
Parity check A type of verification used to check data has been
transmitted accurately; involves the use of a parity bit.
Password A string of characters, often used in conjunction with
a user ID as part of the authentication process when logging
on to a computer or other digital device or software.
Payment Card Industry Data Security Standard (PCI DSS)
Aset of rules helping company websites to process bank card
payments securely and to help reduce card fraud.
Payroll The payment of workers by a company. Payrolls are
usually produced using batch processing at the end of each
week or month.
.pdf See PDF.
PDF (portable document format) A method of allowing
documents to be read/used on most computers. The pages look
just like they would when they are printed but can contain
clickable links and buttons, form fields, video, andaudio. You
can protect a document to stop others editing it.
Penetration test Carried out by companies by employing
somebody to deliberately attack their computer network.
Performance metrics Measure of how well a computer processor
deals with data.
Pharming Malware that when downloaded unknowingly, corrupts
the Hosts file causing the user to be taken to a fake website
when they enter what they regard as an authentic URL.
Phishing When fraudsters try to obtain personal banking details
using email.
Physical variable A measurable property of a material or system
such as temperature, pressure, light and so on.
Pi The number Pi (π) is a mathematical constant. It is
approximately equal to 3.14159 and is used in mathematical
calculations involving circles.
Plaintext Information that is readable by humans or a machine;
the state that text exists in before it is encrypted.
Platter An individual disk within several disks which constitute
a disk drive.
.png See PNG.
PNG (portable network graphics) A format used to save still
images. This is an efficient method of storing images and was
designed to replace .jpg (JPEG). It is widely used in web pages.
Primary key A single field within a relational database table
that contains unique data (no two records within this field
can contain the same data). A primary key field cannot
contain a blank record.
PRINT A statement used in pseudocode to output data; usually
the result of some processing.
Private key A key used in the encryption process to decrypt
a message when using asymmetric encryption but is used
for both encryption and decryption when using symmetric
encryption.
Program flowchart See Flowchart.
Proprietary and open source software Proprietary file formats
are formats belonging to a company, organisation or
individual whose use is controlled by them. The structure of
these file formats is often hidden from others. Open source
file formats are formats used for storing data that are freely
available for anyone to use. The structure of these file
formats is published and available for others to use.
Pseudocode A way of writing algorithms in a language
independent of any programming languages.
Pseudonymised data Like de-identification but instead of
removing the personal items of data they are instead
replaced with a temporary ID.
Public key A key used in the encryption process available to
many users for the purpose of encrypting a message using
asymmetric encryption.
Public key encryption See Asymmetric encryption.
Quality of information A judgement on how good or reliable
information is.
Random access Process of directly accessing data stored on
a non-sequential storage system like HDD or SSD, without
searching through other records to find it.
Ransomware A type of malware hackers use to encrypt a user’s
computer data, which will only be decrypted by the hacker
on receiving payment of a ransom.
.rar See RAR.
RAR (roshal archive) A file format for a container (like a .zip
file) that can hold other files and folders. Its name comes
from Roshal archive and it was developed by a Russian
software engineer, Eugene Roshal.
RAS Measure of reliability, availability and serviceability of
mainframes.
READ A statement used in pseudocode to obtain data from a
file.
Real-time processing The processing of data immediately with
no delay, usually involving the use of sensors.
Record A collection of fields containing information about
one data subject (usually a person) or one object within a
database.
Relational database A database structure where data items are
linked together with relational tables. It maintains a set of
separate, related files (tables), but combines data elements
from the files for queries and reports when required.
352
GLOSSARY
Relative reference Automatically adjusts a cell reference within
a spreadsheet to refer to different cells relative to the
position of the formula during the replication process.
REPEAT…UNTIL A type of loop found in algorithms where the
instructions are executed at least once and then repeated
until the condition is true.
Reverb A shortened form of reverberation, which is an
electronically produced echo effect in recorded music.
Rich text format A file format (.rtf) used for text-based files
that saves the formatting within the document, so allowing
some formatting to be passed from one application package
to another.
RIGHT Function in Microsoft Excel which returns a given number
of characters from the end of a text string.
Rootkit A type of malware that allows an attacker to have
remote access to a victim’s computer continuously.
ROUND Function in Microsoft Excel that rounds a number to a
specified number of decimal places.
ROUNDDOWN Function in Microsoft Excel that rounds a number
down to a specified number of decimal places.
ROUNDUP Function in Microsoft Excel that rounds a number up to
a specified number of decimal places.
.rtf See Rich text format.
Rules base The set of rules applied by an inference engine of
an expert system, usually consisting of series of IF…THEN
statements.
Sandbox A virtual environment within which virus codes are
allowed to be executed to observe their behaviour.
SEARCH Function in Microsoft Excel that returns a number to
represent the position of the first character or text string
that matches a given character or text string.
SECOND Function in Microsoft Excel that returns a number
between 0 and 59 as the number of seconds shown on a clock
from a given time.
Sector Smallest unit of data storage within a disk drive and a
subdivision of a track.
Secure sockets layer (SSL) The predecessor of transport
layer security (TLS); found to have many security flaws
and replaced by TLS which provided greater security when
transmitting data.
Sensor Converts a physical characteristic, such as temperature,
light or pressure, into a signal which can be measured
electrically by a computer.
Sequential access A method of accessing data on a medium, by
having to read through all the preceding data first.
Server A computer that provides data to other computers
connected to it on a network. There are many types of server
including application servers, file servers, mail servers, and
web servers.
Shell The major part of an expert system; usually consists of the
user interface, explanation system, inference engine, and
knowledge base editor.
Signature-based detection A method of detecting viruses based
on recognising existing viruses.
Smart home Uses computers and a router to enable control of
devices within the home.
Smart motorway Section of motorway that uses active traffic
management.
Smishing A variation of phishing whereby an SMS is used rather
than an email to try to obtain personal banking details.
Spyware A type of malware designed to collect information
about a computer user’s activities without their knowledge.
SSH (secure shell) An encryption protocol used to enable
remote logging on to a computer network, securely.
String A type of data that contains characters and may include
text, punctuation, numbers. The term is often interchanged
with the term ‘alphanumeric data’.
SUBTOTAL Function in Microsoft Excel that calculates the
function for a range of value or cells. The parameters passed
to this function determine how it will work; for example it
could be used to calculate the SUM, the AVERAGE and so on.
SUM Function in Microsoft Excel that adds up a list of numbers or
specified cells.
SUMIF Function in Microsoft Excel that looks at the cells within a
given range and adds the total from those cells that meet a
given condition.
SUMIFS Function in Microsoft Excel that looks at the cells within
a given range and adds the total from those cells that meet a
number of given conditions.
Summit A supercomputer which, as of the beginning of 2020,
was the world’s fastest supercomputer.
Supercomputers The largest and fastest computers available.
Symmetric encryption Encryption which uses the same key to
encrypt and decrypt a message, a public key. Often regarded
as a faster process, it is less secure than asymmetric
encryption.
System software Programs that run and control a computer’s
hardware and application software.
Table A two-dimensional grid of data organised by rows and
columns within a database. Each row of the table contains a
record. Each column in the table represents a field and each
cell in that column has the same (predefined) field type.
TEXT Function in Microsoft Excel that changes the formatting of
the current cell from a numeric or date/time value into text
format.
Text file A file format (.txt) used for text-based files that
contain an unformatted ASCII file, although there are file
format variations depending upon the operating system.
These files can be opened in any word processor.
Track Part of the surface of a disk platter which stores data,
with each track containing several sectors.
Transaction In IT terms, when a computer makes an amendment
to a database, be it adding, deleting or changing values in a
record, a transaction is said to have been carried out.
Transaction file A file which contains all ongoing transactions
in a batch-processing system.
Transaction processing A form of processing which can consist
of more than one computer processing operation, but these
operations must combine to form a single transaction.
Transport layer security (TLS) An improved version of the
secure sockets layer (SSL) protocol and which has now
superseded it. The term SSL/TLS is still sometimes used to
bracket the two protocols together. It is used to provide
secure transfer of data when accessing web pages.
Trojan horse A type of malware usually obtained as a result of
the user thinking they have downloaded authentic software.
353
Glossary
It enables the author of the software to take control of the
user’s computer.
.txt See Text file.
UNIVAC 1 First computer produced for general sale in 1951.
UPPER Function in Microsoft Excel that returns a string as only
upper-case characters (capitals).
User ID A string of characters identifying a user when accessing
a computer; nearly always used in association with a
password.
User interface The means by which the user interacts with a
computer system, involving the use of input devices and
software. It is a key component of any computer system but
particularly as part of an expert system.
Utility software Often supplied with the operating system, this
mainly helps to manage files and their associated storage
devices.
Validation A process where the software checks that the
data entered into it is reasonable, often in a database or
spreadsheet.
Verification A process that checks the accuracy of data entry or
that the data has not been corrupted during transmission.
Virus A type of malware that is designed to spread from one
computer to another causing changes in the way each
computer operates.
Vishing A phone call made in order to get an individual to
divulge their personal or banking details.
VLOOKUP Function in Microsoft Excel that looks up data using
data organised in vertical columns.
VPN (virtual private network) Enables a network belonging
to a company or organisation to be extended using a public
network, usually the internet, via tunnelling protocols to
encrypt and decrypt data.
Weather station A system used to monitor the weather in terms
of physical variables such as temperature, rainfall, hours of
sunlight and so on.
WEEKDAY Function in Microsoft Excel that returns a number
between 1 and 7 from a given date. If the day is a Sunday, 1
is returned, Monday is 2, and so on.
WHILE…ENDWHILE A type of loop found in algorithms where
the instructions are repeated while the condition is true.
Worm Self-replicating malware whose sole purpose appears
to be occupying as much disk space and bandwidth as
possible.
WRITE A statement used in pseudocode to output data to
afile.
WSAN (wireless sensor and actuator network) A network of
devices using combined actuators which are called actors
to automatically help the user, such as in a smart parking
system.
YEAR Function in Microsoft Excel that returns the year from a
given date.
.zip See Zip.
Zip To reduce the number of bytes needed to save a file, either
to save storage space or to reduce transmission time.
