Glossary

Looking for web design terms like selector, box model or alt text? They're in the web basics glossary.

Flashcards

Built from the terms shown below, so filter first to practise one content area.

Abstraction

Identifying the information that is needed and filtering out or hiding unnecessary detail.

Acceptable use policy (AUP)

A document setting out how employees or users may and may not use an organisation's IT systems.

Access control list (ACL)

A list that states which users or groups can access a resource and what they can do with it.

Accessibility

Designing systems so that people with disabilities or additional needs can use them.

Air gap

Physically isolating a computer or network from all other networks, including the internet.

Algorithm

A finite, ordered set of unambiguous instructions that solves a problem.

Algorithmic design

Producing a step-by-step set of instructions to solve the problem.

API

Application programming interface: a defined way for one program to request data or services from another.

Argument

The actual value passed to a subroutine when it is called.

Array

An ordered collection of items that are all the same data type.

Artificial intelligence (AI)

Computer systems that perform tasks that normally need human intelligence, such as recognising speech or making predictions.

ASCII

A character set using 7 bits to represent 128 characters (English letters, digits, symbols, control codes).

Asymmetric encryption

Uses a public key to encrypt and a matching private key to decrypt.

Audience exclusion

When some users cannot use or are disadvantaged by a system, e.g. through bias or poor user experience.

Audit log

A record of who did what, and when, in a system.

Augmented reality (AR)

Digital content overlaid on a live view of the real world.

Automation

Using technology to carry out tasks without human involvement.

Autonomous machine

A machine that performs tasks and makes decisions without direct human control, e.g. a self-driving car.

B2B

Business to Business: selling products or services to other businesses.

B2C

Business to Customer: selling directly to individual consumers.

B2M

Business to Many: selling to both businesses and consumers at the same time, often with tailored marketing for each.

Bandwidth

The maximum amount of data that can be transferred per second, measured in bits per second.

Bias (in datasets)

When training data does not fairly represent all groups, so a system's outputs disadvantage some people.

Big Data

Data sets so large, fast-moving or varied that traditional tools can't process them; described by the six Vs.

Binary search

Repeatedly checks the middle item of a sorted list and discards the half that cannot contain the target.

Blob

Binary large object: a data type for storing large binary data such as images, audio or files in a database.

Blockchain

A shared, decentralised ledger of records (blocks) linked using cryptography, so past records cannot be changed without detection.

Block diagram

A diagram of boxes showing how a system is broken down into parts.

Boolean

A value that is either True or False. Python type bool.

Botnet

A network of malware-infected devices (bots) controlled remotely by an attacker.

Bottom-up

Starting with small, detailed components and combining them into a larger solution.

Boundary test data

Data at the edge of what is allowed, and just outside it, e.g. 0, 1, 100, 101 for a 1–100 range.

Brute force

Trying every possible password combination until the right one is found.

Bubble sort

Compares adjacent pairs and swaps them if they are in the wrong order, repeating passes until no swaps are made.

Budapest Convention

The Council of Europe Convention on Cybercrime: an international treaty to harmonise cybercrime laws and help countries cooperate.

Buffer overflow

Sending more data than a memory buffer can hold, so it overwrites nearby memory, possibly running attacker code.

Cache

Small, very fast memory on or near the CPU that stores frequently used instructions and data.

camelCase

Naming style where words are joined and each word after the first starts with a capital: totalPrice.

Casting / type conversion

Changing a value from one data type to another, e.g. int("42").

Categorical data

Data that falls into a limited set of groups, e.g. T-shirt size S/M/L.

Change advisory board (CAB)

A group that reviews, prioritises and approves proposed changes to systems and monitors their implementation.

Character

A data type holding a single letter, digit or symbol.

Check digit

An extra digit calculated from the other digits in a number, used to detect input errors.

CIA triad

Confidentiality, integrity and availability: the three goals of information security.

Clock speed

The number of instruction cycles a CPU can carry out per second, measured in GHz.

Closed box testing

Testing inputs and outputs without looking at the code (also called black box).

Code of conduct

A set of rules and expected behaviours for members of an organisation or profession.

Cold site

A backup location with power and space but no equipment or data set up.

Compiler

Translates the whole source code into machine code in one go, producing an executable file.

Computational thinking

A set of problem-solving techniques for breaking a problem down and expressing a solution so that a computer (or person) could carry it out.

Computer Misuse Act 1990

UK law that makes unauthorised access to and interference with computer systems a criminal offence.

Condition-controlled loop

A loop that repeats while a condition is True (while).

Confidentiality, integrity, availability

The three security properties that a breach can compromise (the CIA triad).

Constant

A named value that does not change while the program runs. In Python, written in CAPITALS by convention.

Continuing professional development (CPD)

Ongoing learning to keep skills and knowledge up to date throughout a career.

Continuous data

Numeric data that can take any value in a range, usually measured, e.g. height.

Core

An independent processing unit within a CPU. More cores means more instructions can be processed at the same time.

Count-controlled loop

A loop that repeats a set number of times (for).

CRC

Cyclic redundancy check: an error-detection value calculated from the packet's data and checked by the receiver.

CRM

Customer relationship management: systems that store and analyse customer data and manage communications.

Cross-site scripting (XSS)

Injecting malicious script into a website so it runs in other users' browsers.

CSV

Comma-separated values: a plain text format where each line is a record and fields are separated by commas.

Data

Raw facts and figures with no context, e.g. 18, 22, 25.

Data controller

The organisation that decides why and how personal data is processed.

Data integrity

Data remains accurate, complete and consistent throughout its life.

Data lake

A store holding large amounts of raw data in any format until it is needed.

Data mart

A smaller subset of a data warehouse focused on one department or topic.

Data mining

Using algorithms to find hidden patterns and relationships in large data sets.

Data processor

An organisation that processes personal data on behalf of a controller, e.g. a cloud payroll provider.

Data redundancy

The same data stored in more than one place. Unplanned redundancy causes inconsistency; planned redundancy (backups) improves resilience.

Data subject

The living person the personal data is about.

Data warehouse

A central store of structured, cleaned data from many sources, organised for reporting and analysis.

Data wrangling

Transforming raw data into a clean, structured format ready for analysis.

Debugging

Locating and correcting errors in code.

Decision

Flowchart symbol (diamond) for a question with two or more outcomes, such as Yes/No.

Decomposition

Breaking a problem or solution down into smaller, more manageable parts.

Device hardening

Reducing a device's attack surface by removing unneeded ports, applications, permissions and access.

Dictionary

A collection of key–value pairs. Values are looked up by key rather than position.

Digital divide

The gap between people who have access to digital technology and the skills to use it, and those who do not.

Digital footprint

The trail of data a person leaves online: posts, searches, purchases, location history. Can be active (things you share) or passive (data collected about you).

Digital identity

The information that represents a person online: accounts, profiles, usernames, reputation.

Digital inclusion

Making sure everyone can access and use digital services, whatever their circumstances.

Direct discrimination

Treating someone less favourably because of a protected characteristic.

Direct implementation

Switching off the old system and starting the new one at the same moment (big bang).

Discrete data

Numeric data that can only take specific values, usually counted, e.g. number of tickets.

Display screen equipment (DSE)

Devices with a screen: monitors, laptops, tablets, smartphones used for work.

DoS / DDoS

Denial of service: flooding a system with traffic so legitimate users can't access it. Distributed DoS uses many devices at once.

Downtime

Time when a system is unavailable.

DSE workstation assessment

A check of a user's desk, chair, screen, keyboard and working habits to reduce health risks.

Edge computing

Processing data close to where it is created (on or near the device) rather than sending it all to a central cloud server.

Elasticity

The ability of cloud resources to scale up or down automatically to match demand.

Embedded device

A computer built into a larger device to perform one dedicated function, e.g. in a washing machine or car.

Encryption

Scrambling data with a key so only someone with the correct key can read it.

Erroneous test data

Data of the wrong type that should be rejected, e.g. "ten" when a number is expected.

Escalate

Pass a problem to someone with more authority or expertise: a manager, specialist or external third party.

Event tree analysis

A diagram that starts from one initiating event and branches through success/failure of each safeguard to show possible outcomes.

E-waste

Discarded electrical and electronic equipment.

Exception

An error object raised at runtime. Can be caught with try/except.

Extended reality (XR)

Umbrella term for augmented reality and virtual reality.

Feasibility

Whether a project is practical and worthwhile given its benefits, risks and constraints.

Feedback loop (AI)

When an AI system's outputs influence the data it is later trained on, which can reinforce errors or bias.

Firewall

Hardware or software that controls network traffic in and out using rules.

Firmware

Software stored on hardware that controls the device at a low level.

Five whys

Asking 'why?' repeatedly (often five times) to move from a symptom to the root cause.

Float

A number with a decimal (fractional) part. Python type float.

Flowchart

A diagram that shows an algorithm using standard symbols joined by arrows.

FMEA

Failure mode and effects analysis: listing how each part could fail, the effect, and rating severity, likelihood and detection to prioritise action.

Foreign key

A field in one table that is the primary key of another table, creating a link.

Function

A named subroutine that may take parameters and must return a value.

Generative AI

AI that creates new content (text, images, video, audio) from a prompt, based on patterns learned from training data.

Globalisation

The increasing connection of economies, cultures and media across the world.

Global variable

A variable declared outside any function, which can be read anywhere in the program.

GPU

Graphics processing unit: a processor with many cores designed for parallel processing of graphics and large calculations.

Harassment

Unwanted behaviour related to a protected characteristic that violates someone's dignity or creates a hostile environment.

Hashing

A one-way function that turns data into a fixed-length value. It cannot be reversed.

Health and Safety at Work Act 1974

Main UK law setting out the duties of employers and employees to keep the workplace safe.

Hierarchical markers

Numbering such as 1, 1.1, 1.2, 2 used in written descriptions to show the order and nesting of steps.

Hierarchical model

Data organised as a tree: each child record has one parent.

Hot site

A fully equipped backup site with up-to-date data that can take over almost immediately.

Hybrid working

Splitting working time between the office and home.

Hypervisor

Software that creates and runs virtual machines and shares physical hardware between them.

IAAA

Identification, authentication, authorisation, accountability: the stages of controlling access to a system.

IaaS

Infrastructure as a Service: the provider supplies virtualised hardware; the client manages everything from the OS up.

IDE

Integrated development environment: software that combines a code editor, debugger and other tools for programming.

Index

The position of an item in a list, array or string. Python starts counting at 0.

Indirect discrimination

A rule or practice that applies to everyone but puts people with a protected characteristic at a particular disadvantage, without good justification.

Industry standard

An agreed specification or set of best practices that products, processes or services should meet.

Information

Data that has been processed and given context so it has meaning, e.g. 'Temperatures in Leeds this week: 18–25°C'.

Information Commissioner's Office (ICO)

The UK regulator for data protection. It can investigate, issue fines and enforce compliance.

Information flow diagram

A diagram showing how information moves between people, systems and processes.

Insertion sort

Builds a sorted section one item at a time by inserting each item into its correct position.

Integer

A whole number, positive, negative or zero. Python type int.

Integration testing

Testing that components work correctly together.

Intellectual property (IP)

Creations of the mind, such as inventions, designs and creative works, that can be legally owned.

Internet of Things (IoT)

Everyday physical devices with sensors and network connections that collect and share data.

Interpreter

Translates and runs source code one line at a time.

Interrupt

A signal to the processor that something needs attention immediately.

Intrusion detection system (IDS)

Monitors network or system activity and alerts on suspicious behaviour.

Invalid test data

Data of the correct type that should be rejected because it breaks a rule, e.g. age = 150.

Iteration

Repeating a block of code (a loop).

JSON

JavaScript Object Notation: a lightweight text format storing data as key–value pairs and arrays, widely used by web APIs.

Knowledge

Understanding gained from information that can be applied to make decisions, e.g. 'Ice cream sales rise above 20°C, so order more stock'.

KPI

Key performance indicator: a measurable value showing how well an organisation is achieving its objectives.

Large enterprise

An organisation with 250 or more employees.

Latency

The time delay for data to travel from source to destination, measured in milliseconds.

Legacy system

An older system still in use that new systems may need to work with.

Library

A collection of pre-written code that can be imported, e.g. math, random.

Linear search

Checks each item in turn from the start until the target is found or the list ends.

List

An ordered, changeable collection of items that can hold mixed data types and grow or shrink.

Local variable

A variable declared inside a function. It only exists while that function runs.

Logic error

The program runs but gives the wrong result.

Machine learning

A type of AI where a system learns patterns from data and improves its predictions without being explicitly programmed for each case.

Malware

Malicious software, e.g. viruses, worms, ransomware, spyware.

Man-in-the-middle (MitM)

Secretly intercepting and possibly altering communication between two parties.

Merge sort

Splits a list into single items, then merges them back together in order.

Metadata

Data about data, e.g. a photo's date, location, file size and camera model.

Modularisation

Splitting a solution into self-contained modules that can be developed and tested separately.

Musculoskeletal disorder

Injury or pain in muscles, joints or tendons, e.g. back pain or repetitive strain injury (RSI).

Network model

Data organised as a graph: records can have many parents and many children (many-to-many).

NGO

Non-governmental organisation: independent of government, usually working for a social or environmental cause.

Open box testing

Testing with knowledge of the code, checking every path runs correctly (also called white box).

Open source software

Software whose source code is published so anyone can view, modify and distribute it under its licence.

Operating system

Software that manages hardware and resources and provides a platform for applications.

PaaS

Platform as a Service: the provider supplies hardware, OS and runtime; the client manages applications and data.

Package manager

A tool that installs, updates and removes software and its dependencies, e.g. pip, apt.

Packet

A small unit of data sent across a network, containing a header, payload and trailer.

Packet switching

Splitting data into packets that travel independently across a network and are reassembled at the destination.

Pain point

A specific problem or frustration users experience with a product or service.

Parallel implementation

Running the old and new systems side by side for a period.

Parameter

A variable listed in a subroutine definition that receives a value when the subroutine is called.

Patent

Legal protection for a new invention that gives the owner the right to stop others making, using or selling it, for up to 20 years.

Pattern recognition

Finding similarities and trends within and between problems so existing solutions can be reused.

Penetration testing

An authorised, simulated attack to find vulnerabilities before real attackers do.

Personal data

Any information that can identify a living person, directly or indirectly.

PESTLE

Political, Economic, Social, Technological, Legal, Environmental: the external factors that trigger change.

Pharming

Redirecting users from a genuine website to a fake one, e.g. by tampering with DNS.

Phased implementation

Introducing the new system one part (module) at a time.

Phishing

Fake emails pretending to be from a trusted source, to steal details or spread malware.

Pilot implementation

Introducing the new system in one location or to one group first, then rolling it out.

Port scanning

Checking which network ports on a device are open and what services are listening.

Primary key

A field that uniquely identifies each record in a table.

Private sector

Organisations owned by individuals or shareholders, usually aiming to make a profit.

Procedure

A named subroutine that may take parameters and does not return a value.

Protected characteristic

One of nine characteristics protected from discrimination under the Equality Act 2010.

Protocol

A set of rules that govern how data is transmitted and received.

Public sector

Organisations owned and funded by the government to provide public services.

Qualitative data

Descriptive data such as opinions, text, images or video.

Quantitative data

Data that can be measured or counted as numbers.

Quantum computing

Computing that uses qubits, which can represent 0 and 1 at the same time, to solve certain problems far faster than conventional computers.

RAM

Random access memory: volatile main memory that holds the programs and data currently in use.

Ransomware

Malware that encrypts files and demands payment for the key.

Rare earth metals

Elements such as neodymium used in electronics; mining them causes environmental damage and supplies are limited.

RBAC

Role-based access control: permissions given according to the user's role.

Real

A data type for numbers with a fractional part (float in Python).

Redundancy

Having duplicate components or data so that if one fails, another takes over.

Registered design

A design registered with the Intellectual Property Office, protecting its appearance for up to 25 years.

Regression testing

Re-running earlier tests after a change to check nothing that worked before is now broken.

Relational model

Data organised in tables linked by primary and foreign keys.

Remote access trojan (RAT)

Malware disguised as legitimate software that gives an attacker remote control of a device.

Requirement traceability

Being able to link each change back to the requirement it meets and who was responsible.

Robust code

Code that handles unexpected inputs and terminations and gives specific, meaningful error messages.

Rollback

Returning to the previous version of a system if a change fails.

ROM

Read-only memory: non-volatile memory that holds the startup instructions (firmware/BIOS).

Root cause analysis

A process for finding the underlying cause of a problem, rather than just treating the symptoms.

Router

Forwards data packets between different networks using IP addresses.

RuBAC

Rule-based access control: access decided by rules, e.g. time of day or location.

Runtime error

An error that happens while the program is running, causing it to crash, e.g. dividing by zero.

SaaS

Software as a Service: the provider supplies the complete application; the client manages users and data.

Scope

The part of a program where a variable can be accessed.

Selection

Choosing which code to run based on a condition (if, elif, else, match/case).

Sequence

Instructions run one after another in the order written.

Server

A computer that provides services or resources (files, web pages, email) to other computers on a network.

Shoulder surfing

Watching someone enter a password or PIN, or read their screen.

SMARTER

Specific, Measurable, Achievable, Realistic, Time-bound, Evaluated, Reviewed: a framework for setting objectives.

SME

Small or medium-sized enterprise: fewer than 250 employees (small: fewer than 50).

Smishing

Phishing by SMS text message.

snake_case

Naming style where words are lower case and joined with underscores: total_price. Recommended for Python variables.

Social engineering

Manipulating people into giving away information or access.

Spear phishing

Phishing targeted at a specific person or organisation, using personal details to seem genuine.

SQL injection

Entering SQL code into an input field so it is run by the database, to read, change or delete data.

Stakeholder

Anyone with an interest in, or affected by, an organisation.

Standard operating procedure (SOP)

A written, step-by-step instruction for carrying out a routine task consistently.

String

A sequence of characters, written in quotes. Python type str.

Structured data

Data organised in a fixed format, such as rows and columns in a table.

Subject access request (SAR)

A request from an individual to see the personal data an organisation holds about them.

Sub-process

Flowchart symbol (rectangle with double sides) for a predefined process described elsewhere, such as a function.

Surveillance

Monitoring people's behaviour or communications, by governments, employers or companies.

Switch

Connects devices within a LAN and forwards data only to the device it is addressed to, using MAC addresses.

Symmetric encryption

Uses the same key to encrypt and decrypt.

Syntax error

Code that breaks the rules of the language, so it cannot run.

Tailgating

Following an authorised person through a secure door without using your own access.

Terminator

Flowchart symbol (rounded rectangle) for the start or end of an algorithm.

Test plan

A document listing the tests to run, their purpose, the test data, expected results and actual results.

Threat

Something that could cause harm to a system or data, e.g. a hacker or malware.

Time-slicing

Giving each task a short slot of processor time in turn, so several tasks appear to run at once.

Top-down

Starting with the whole problem and breaking it into smaller sub-problems.

Topology

The arrangement of devices and connections in a network.

Trace table

A table used to record variable values line by line as an algorithm runs.

Transcription error

A mistake made when copying data, e.g. typing 'Smtih' for 'Smith' or a wrong digit.

Transposition error

Two characters swapped, e.g. 1243 instead of 1234.

Unit testing

Testing one component (e.g. a function) on its own.

Unregistered design right

Automatic protection for the shape or configuration of a product, without applying.

Unstructured data

Data with no predefined format, such as emails, images and audio.

UTF-8

A variable-length Unicode encoding (1–4 bytes per character) that can represent characters from every language and emoji, and is backwards compatible with ASCII.

Utility

System software that maintains or optimises the computer, e.g. backup, compression.

Validation

Automatic checks that input data is sensible and follows rules before it is accepted. It does not check data is correct.

Valid test data

Data that should be accepted and processed normally.

Variable

A named location in memory that stores a value which can change while the program runs.

Veracity

How accurate and trustworthy data is.

Verification

Checking data has been entered or transferred accurately, e.g. double entry or proofreading.

Version control

Software that tracks every change to files, who made it and when, so earlier versions can be restored (e.g. Git).

Victimisation

Treating someone badly because they made or supported a discrimination complaint.

Virtual machine (VM)

A software-based computer that runs an operating system and applications like a physical machine.

Virtual reality (VR)

A fully computer-generated environment that replaces the user's view of the real world.

Virus

Malware that attaches to a file or program and spreads when that file is run or shared.

Vishing

Phishing by voice call.

Volatile

Loses its contents when the power is switched off.

Voluntary / charity sector

Not-for-profit organisations that use any surplus for their cause.

Vulnerability

A weakness that a threat could exploit, e.g. unpatched software or a weak password policy.

Watering hole attack

Infecting a website that a target group is known to visit.

WCAG

Web Content Accessibility Guidelines: the international standard for accessible web content, built on four principles (perceivable, operable, understandable, robust).

Whistleblowing

Reporting wrongdoing within an organisation, such as illegal activity or danger to the public.

Worm

Malware that replicates itself and spreads across networks without user action.

XML

Extensible Markup Language: a text format that uses custom tags to describe and structure data.

Zero-day

A vulnerability unknown to the vendor, with no patch available.

Zero-day vulnerability

A security flaw unknown to the vendor, with no patch available, that attackers can exploit.