Full forms: computers and internet

62 full forms, each with a line on what it means.

Computing has more short forms than any other field, because its long technical names are used so often. This page gathers the ones met in school computer science, on specification sheets when buying a device, and in everyday use of the web: the parts of a computer, units of storage, file types, and the words of networks and the internet. A few entries are not what people think. Wi-Fi and ZIP (the file format) are names, not initials, and the page says so plainly. Where a term is commonly misused, such as "CPU" for the whole cabinet or "ROM" for phone storage, the entry gives the strict meaning that an examiner expects.

Explained in full: PDF CPU RAM HTML

• CPU

  Central Processing Unit

  The main chip of a computer, which carries out instructions. People also use the word for the whole system box, though that is not strictly correct.

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• RAM

  Random Access Memory

  The working memory of a computer or phone, which holds running programs and is emptied when the power goes off.

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• ROM

  Read Only Memory

  Memory whose contents are fixed and not lost when the power goes off. Phone makers also use the word loosely for storage.

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• HDD

  Hard Disk Drive

  A storage device that keeps data on spinning magnetic disks.

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• SSD

  Solid State Drive

  A storage device with no moving parts, much faster than a hard disk.

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• USB

  Universal Serial Bus

  The standard plug and cable system for connecting and charging devices.

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• OS

  Operating System

  The main software, such as Windows, Android, iOS or Linux, that runs a device and its apps.

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• PC

  Personal Computer

  A computer meant for one person's use, such as a desktop or laptop.

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• GUI

  Graphical User Interface

  A way of using a computer through windows, icons and menus instead of typed commands.

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• BIOS

  Basic Input Output System

  The built-in program that starts a computer and hands over to the operating system.

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• GPU

  Graphics Processing Unit

  A chip designed to draw images quickly, also used for artificial intelligence work.

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• UPS

  Uninterruptible Power Supply

  A battery unit that keeps a computer running for a short time during a power cut.

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• LAN

  Local Area Network

  A network that links computers within one building or campus.

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• WAN

  Wide Area Network

  A network that covers a large area, linking distant places.

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• WLAN

  Wireless Local Area Network

  A local network that uses radio signals in place of cables.

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• Wi-Fi

  no full form

  Wi-Fi is a brand name of the Wi-Fi Alliance for wireless networking. It is often expanded as "Wireless Fidelity", but that phrase was only an early advertising slogan.

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• IP

  Internet Protocol

  The set of rules for addressing and sending data across the internet. An IP address identifies a device on a network.

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• URL

  Uniform Resource Locator

  The address of a page or file on the web, such as https://example.com/page.

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• WWW

  World Wide Web

  The system of linked pages reached through the internet with a browser.

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• HTTP

  Hypertext Transfer Protocol

  The set of rules a browser and a web server use to exchange pages.

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• HTTPS

  Hypertext Transfer Protocol Secure

  HTTP with encryption, so that others cannot read the data on its way.

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• HTML

  Hypertext Markup Language

  The language in which web pages are written.

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• CSS

  Cascading Style Sheets

  The language that sets the look of a web page: colours, fonts and layout.

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• PDF

  Portable Document Format

  A file format that keeps a document looking the same on every device and printer.

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• JPEG

  Joint Photographic Experts Group

  A common compressed format for photographs, named after the committee that created it. Files end in .jpg or .jpeg.

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• PNG

  Portable Network Graphics

  An image format that keeps sharp edges and allows transparent backgrounds.

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• GIF

  Graphics Interchange Format

  An image format best known for short, silent, looping animations.

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• MP3

  MPEG Audio Layer 3

  A compressed audio format. MPEG stands for Moving Picture Experts Group.

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• MP4

  MPEG-4 Part 14

  A common file format for video with sound.

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• ZIP

  Zone Improvement Plan

  As in the ZIP code of a United States postal address. The ZIP file format for compressed files is a different thing: its name is a word chosen to suggest speed, not initials.

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• DNS

  Domain Name System

  The system that turns a website name into the numeric address computers use.

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• ISP

  Internet Service Provider

  A company that gives you an internet connection.

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• VPN

  Virtual Private Network

  A service that sends your internet traffic through an encrypted tunnel to another server.

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• AI

  Artificial Intelligence

  Computer systems that do tasks which normally need human intelligence, such as understanding language.

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• ML

  Machine Learning

  A branch of artificial intelligence in which programs learn patterns from data.

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• SQL

  Structured Query Language

  The language used to store and fetch data in relational databases.

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• API

  Application Programming Interface

  A defined way for one program to ask another for data or services.

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• IT

  Information Technology

  The use of computers, software and networks to handle information; also the industry built around it.

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• ICT

  Information and Communication Technology

  A wider term than IT that also covers telephones, broadcasting and the internet.

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• CD

  Compact Disc

  An optical disc for music or data.

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• DVD

  Digital Versatile Disc

  An optical disc that holds much more than a CD, used for films. It is also expanded as Digital Video Disc.

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• LED

  Light Emitting Diode

  A small electronic part that gives light when current passes through it, used in bulbs and screens.

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• LCD

  Liquid Crystal Display

  A flat screen technology that uses liquid crystals lit from behind.

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• OLED

  Organic Light Emitting Diode

  A screen technology in which each dot gives its own light, allowing true black.

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• HD

  High Definition

  A video picture of 1280 × 720 dots or more; Full HD is 1920 × 1080.

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• KB

  Kilobyte

  A unit of data: about a thousand bytes.

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• MB

  Megabyte

  A unit of data: about a million bytes.

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• GB

  Gigabyte

  A unit of data: about a thousand megabytes.

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• TB

  Terabyte

  A unit of data: about a thousand gigabytes. In medicine TB means tuberculosis.

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• OCR

  Optical Character Recognition

  Software that turns a picture of text into text you can edit.

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• QR

  Quick Response

  As in QR code: a square pattern that a phone camera reads at once, used for payments and links.

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• CAPTCHA

  Completely Automated Public Turing test to tell Computers and Humans Apart

  A small test on a website to check that the visitor is a person and not a program.

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• COBOL

  Common Business Oriented Language

  An early programming language still used in banking systems.

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• ASCII

  American Standard Code for Information Interchange

  An early standard that gives a number to each English letter, digit and sign.

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• CCTV

  Closed Circuit Television

  A system of security cameras whose pictures go to a limited set of screens or recorders.

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• CC

  Carbon Copy

  In email, a field for people who should receive a copy. The term comes from carbon paper. For engines, cc means cubic centimetres.

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• BCC

  Blind Carbon Copy

  An email field for recipients whose addresses are hidden from the others.

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• FAQ

  Frequently Asked Questions

  A list of common questions with their answers.

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• SEO

  Search Engine Optimisation

  The work of making a website easier for search engines to find and rank.

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• IoT

  Internet of Things

  Everyday objects, such as meters and cameras, that are connected to the internet.

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• MS

  Microsoft

  As in MS Word or MS Excel: a short form of the company name.

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• PPT

  PowerPoint Presentation

  A slide file made in Microsoft PowerPoint; also used loosely for any slide presentation.

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How to read an entry

The letters in bold are the short form as it is normally written. Under it is the full form, and then a line of meaning in plain words. Where the same letters mean something else in another field, the entry mentions it. "Copy" puts the short form, the full form and the meaning on your clipboard, ready to paste into notes or a message.

Check what matters. These pages explain names and terms in general. Rules, dates, fees and limits change: take them from the official body. Read on 12 November 2026.

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