Have you ever come across a computer term that you did not understand? You are not alone. The world of computers is full of technical words, abbreviations, and jargon that can be confusing — especially for beginners. That is exactly why we created this complete computer glossary.
In this article, you will find a simple and easy-to-understand explanation of all the important computer terms from A to Z. Whether you are a student preparing for exams, someone starting a new job, or just a curious learner — this computer glossary will be your go-to reference guide. Bookmark this page and come back to it whenever you need a quick explanation of any computer term.
Why Is a Computer Glossary Important?
Understanding computer terminology is important for several reasons:
- Exam preparation: Computer terms are frequently asked in competitive exams like SSC, IBPS, and RRB.
- Job interviews: Employers expect candidates to know basic computer terminology.
- Better understanding: Knowing the meaning of terms helps you use computers more confidently and effectively.
- Communication: In a workplace, being able to understand and use correct computer terms makes communication clearer.
- Self improvement: Building your computer vocabulary is a great way to improve your overall digital literacy.
Before we dive into the glossary, you might also want to check out our Computer Basic Quiz to test your knowledge, and our Computer Awareness guide for a complete overview of important computer concepts.
Computer Glossary — Letter A
Active Cell
In Microsoft Excel, the active cell is the currently selected cell that is highlighted with a dark border. Any data you type will be entered into the active cell. It is identified by its cell address, such as A1 or B3. The active cell plays an important role in data entry and formula application.
Address
In computing, an address is a unique identifier that points to a specific location in memory, a register, or a data source. Just like your home has an address so people can find it, every location in computer memory has an address so the CPU can find and access data stored there.
ALU — Arithmetic Logic Unit
The ALU is a part of the CPU that performs all mathematical calculations (addition, subtraction, multiplication, division) and logical operations (comparisons like greater than, less than, equal to). Without the ALU, a computer cannot perform any calculations. It is one of the three main components of the CPU along with the Control Unit and Memory Unit.
Application Program
An application program (also called application software or simply an app) is a computer program designed to help users perform specific tasks. Examples include Microsoft Word for writing documents, Microsoft Excel for spreadsheets, VLC for watching videos, and Google Chrome for browsing the internet. Application programs are different from system software which runs in the background.
Application Software
Application software is designed to perform a specific task for the user. It runs on top of system software (like Windows or macOS). Common examples include word processors, spreadsheet programs, media players, and web browsers. Application software can be divided into general-purpose software (like MS Word) and specialized software (like accounting or hospital management systems).
ASCII — American Standard Code for Information Interchange
ASCII is a character encoding standard that assigns a unique number to each letter, digit, punctuation mark, and control character. For example, the uppercase letter A is represented as 65 in ASCII. Computers use ASCII to convert keyboard input into binary code that they can process. It was one of the first character encoding standards and is still widely used today.
Computer Glossary — Letter B
Bandwidth
Bandwidth refers to the maximum amount of data that can be transmitted over a network connection in a given amount of time. It is usually measured in Mbps (Megabits per second) or Gbps (Gigabits per second). Higher bandwidth means faster internet and quicker data transfers. Think of bandwidth like a highway — the wider the highway, the more cars (data) can travel at once.
Batch Processing
Batch processing is a method of processing data where a group (batch) of tasks is collected together and processed all at once, without any user interaction during processing. It is commonly used for payroll processing, bank statement generation, and printing large volumes of documents. The main advantage is that it is efficient and saves time.
Binary Code
Binary code is the most fundamental language of computers. It uses only two digits — 0 and 1. Every piece of data, every instruction, and every program in a computer is ultimately stored and processed as a combination of 0s and 1s. The word binary means two, which is why this system only uses two digits. For example, the letter A in binary is 01000001.
BIOS — Basic Input Output System
BIOS is a firmware program stored in a ROM chip on the motherboard. It is the first software that runs when you turn on your computer. BIOS checks all the hardware components (called POST — Power-On Self Test) and then loads the operating system from the hard drive. Without BIOS, your computer cannot start up.
Bit
A bit (short for binary digit) is the smallest unit of data in a computer. It can only have one of two values — 0 or 1. All computer data is ultimately made up of bits. Eight bits together make one byte. Bits are used to measure data transfer speeds (like Mbps — Megabits per second).
Boot
Booting means starting up a computer. There are two types of booting: Cold Boot means starting the computer from a completely powered-off state. Warm Boot (also called Restart) means restarting the computer without completely turning off the power. During the boot process, the BIOS runs, hardware is checked, and the operating system is loaded.
Boot Loader
A boot loader is a small program stored in the computer’s memory that reads and loads the main portion of the operating system from secondary storage (like the hard drive) into RAM when the computer starts. It acts as a bridge between the BIOS and the operating system.
Bug
A bug is an error, flaw, or fault in a computer program or hardware that causes it to produce incorrect results or behave unexpectedly. The process of finding and fixing bugs is called debugging. The term bug was popularized when an actual moth was found causing problems in an early computer back in 1947.
Byte
A byte is a unit of digital information that consists of 8 bits. It is the basic unit used to measure file sizes and storage capacity. One byte can represent a single character like the letter A. Larger units include Kilobyte (KB = 1024 bytes), Megabyte (MB = 1024 KB), Gigabyte (GB = 1024 MB), and Terabyte (TB = 1024 GB).
Computer Glossary — Letter C
CAD-CAM
CAD stands for Computer Aided Design and CAM stands for Computer Aided Manufacturing. CAD software is used by engineers and designers to create detailed 2D and 3D designs of products. CAM software then uses those designs to control manufacturing machines. Together, CAD-CAM has revolutionized industries like automobile manufacturing, aerospace, and architecture.
Cell
In Microsoft Excel, a cell is the basic unit where data is entered. Cells are created by the intersection of rows and columns. Each cell has a unique address made up of the column letter and row number, such as A1, B2, or C5. You can enter text, numbers, or formulas in a cell.
Cell Pointer
The cell pointer is the highlighted border around the active cell in Microsoft Excel. It shows you exactly which cell is currently selected. You can move the cell pointer using the arrow keys on your keyboard or by clicking on any cell with your mouse.
CGI — Common Gateway Interface
CGI is a standard protocol that allows web servers to execute programs and scripts in response to user requests. When you fill out a form on a website and submit it, CGI scripts often process that information and generate a response page. It was one of the earliest ways to create dynamic web content.
Cookie
A cookie is a small text file that a website stores on your computer when you visit it. Cookies are used to remember your preferences, login status, and browsing history. For example, when a website remembers your username and password, it is using cookies. Cookies can be helpful but also raise privacy concerns, which is why websites now ask for your consent before storing cookies.
Copyright
Copyright is a legal right that gives the creator of original work exclusive rights over its use and distribution. In the context of computers and software, copyright means that you cannot copy, distribute, or use software without the permission of its creator. Violating copyright is illegal and can result in serious legal consequences.
Counterfeiting
Counterfeiting in computing refers to the illegal process of making and distributing unauthorized copies of software packages, often with fake packaging that looks like the original. Counterfeit software is usually sold at a much lower price but may contain viruses or malware. Always buy software from trusted sources.
Cracker
A cracker is a person who illegally breaks into computer systems to steal information, damage files, or gain unauthorized access. Unlike a hacker (who may break into systems for legitimate security research), a cracker always has malicious intent. Crackers are responsible for many data breaches and cyberattacks.
CPU — Central Processing Unit
The CPU is called the brain of the computer. It is the primary component responsible for executing instructions from programs. The CPU processes all data and controls all other parts of the computer. Modern CPUs have multiple cores (like dual-core or quad-core) which allow them to process multiple tasks simultaneously. Learn more about computer hardware on our site.
CU — Control Unit
The Control Unit is a component of the CPU that directs and coordinates all activities of the computer. It fetches instructions from memory, decodes them, and directs the ALU, memory, and input/output devices to execute them. The CU does not process data itself but tells other parts what to do and when.
Cursor
A cursor is a visual indicator on a computer screen that shows where the next input will appear. The text cursor (also called the caret) is the blinking vertical line that shows where typed text will be inserted. The mouse cursor (also called the pointer) is the arrow or hand icon that moves when you move your mouse.
Computer Glossary — Letter D
Data
Data refers to raw, unprocessed facts and figures without any context or meaning. For example, numbers like 45, 78, 92 are data. When data is processed and given meaning, it becomes information. In computers, data can be in the form of text, numbers, images, audio, or video.
Data Capture
Data capture is the process of collecting data from a source and converting it into a format that a computer can process. Data can be captured manually (through keyboard input) or automatically (through sensors, scanners, or cameras). Accurate data capture is the first and most important step in any data processing system.
Data Manipulation
Data manipulation refers to the process of modifying, organizing, or transforming captured data to produce useful information. This can include sorting data, performing calculations, filtering records, or creating summaries. Database management systems (DBMS) are commonly used for data manipulation.
Data Processing
Data processing is the series of operations that transform raw data into meaningful information. The process involves collecting data, processing it through calculations or sorting, and presenting the results as useful output. Examples include generating payroll, creating reports, and processing exam results.
Database
A database is an organized collection of structured data that is stored and accessed electronically. Data in a database is stored in tables (rows and columns) and can be easily searched, sorted, and retrieved. Common database software includes MySQL, Microsoft Access, and Oracle. Databases are used everywhere — from hospitals and banks to e-commerce websites.
DBMS — Database Management System
A DBMS is a software package that allows users to create, manage, and access databases. It provides tools for storing data, retrieving data, updating records, and ensuring data security. Popular DBMS software includes MySQL, Oracle, Microsoft SQL Server, and PostgreSQL.
Debug
Debugging is the process of finding and fixing errors (bugs) in a computer program or hardware system. Every programmer goes through debugging regularly. Modern code editors have built-in debugging tools that help identify where an error is occurring in the code. Good debugging skills are essential for any software developer.
DHTML — Dynamic HyperText Markup Language
DHTML is a combination of HTML, CSS, and JavaScript that allows web pages to be interactive and change dynamically without needing to reload the entire page. With DHTML, elements on a page can move, change color, or respond to user actions like mouse clicks. It was a major step forward in creating interactive websites.
Dial-Up Networking
Dial-up networking is a method of connecting to the internet using a telephone line and a modem. The computer dials a phone number to connect to an Internet Service Provider (ISP). Dial-up was the primary way people connected to the internet in the 1990s but has largely been replaced by broadband connections like DSL, cable, and fiber optic.
Disk Drive
A disk drive is the hardware device that reads from and writes to a storage disk. This includes hard disk drives (HDD) which use spinning magnetic disks, optical drives which read CDs and DVDs, and floppy disk drives which are now obsolete. Disk drives are essential for storing the operating system, programs, and user files.
DOS — Disk Operating System
DOS is one of the earliest operating systems for personal computers. It uses a command-line interface where users type text commands to interact with the computer. MS-DOS (Microsoft Disk Operating System) was the dominant OS before Windows was introduced. While mostly replaced by graphical operating systems, knowledge of DOS commands is still useful for troubleshooting.
Computer Glossary — Letter E
Email — Electronic Mail
Email is a method of exchanging digital messages over the internet. You can send text, files, images, and documents to anyone in the world instantly using email. Popular email services include Gmail, Outlook, and Yahoo Mail. Email has largely replaced traditional postal mail for business and personal communication.
Ethernet Card
An Ethernet card (also called a Network Interface Card or NIC) is a hardware component inside a computer that allows it to connect to a wired network using an Ethernet cable. It provides the physical connection between your computer and the router or network switch. Most modern computers have an Ethernet port built directly into the motherboard.
Ethics in Computing
Computer ethics refers to the set of moral principles and rules that govern the use of computers and the internet. This includes respecting others’ privacy, not hacking into systems, not copying software illegally, and being honest online. Good computer ethics are essential for a safe and trustworthy digital environment.
Computer Glossary — Letter F
Field
In a database, a field is a single piece of information stored for each record. For example, in a student database, fields might include Name, Age, Roll Number, and Grade. A collection of related fields makes up a record. Fields are like the columns in a table.
File
A file is a collection of related data stored together under a single name on a storage device. Files can contain text, images, audio, video, or program code. Every file has a name and an extension that tells the computer what type of file it is. Learn more about file extensions on our site.
Firewall
A firewall is a security system (hardware or software) that monitors and controls incoming and outgoing network traffic based on predetermined security rules. It acts as a protective barrier between your computer or network and the internet, blocking unauthorized access while allowing legitimate communication. Both Windows and macOS have built-in firewall software.
Computer Glossary — Letters G and H
GML — General Markup Language
GML is a markup language developed by IBM in the 1960s that was used to define the structure and formatting of documents. It was the predecessor to SGML (Standard Generalized Markup Language) and eventually HTML. GML introduced the concept of using tags to describe document structure.
Hacker
A hacker is a person with deep knowledge of computer systems who uses that knowledge to gain access to systems. The term can mean different things: White Hat Hackers are ethical hackers who help organizations find security vulnerabilities. Black Hat Hackers are malicious hackers who break into systems for personal gain. Grey Hat Hackers fall somewhere in between.
HTML — HyperText Markup Language
HTML is the standard language used to create web pages. It uses tags (like <h1>, <p>, <img>) to define the structure and content of a web page. When you visit any website, your browser reads the HTML code and displays it as a formatted page. HTML is the foundation of all websites on the internet.
Computer Glossary — Letter I
Input Unit
The input unit is the part of a computer system that accepts data and instructions from the outside world. It converts the input into a form that the computer can process. Common input devices include the keyboard, mouse, scanner, microphone, and webcam. You can read more about input devices on our site.
Internet Society
The Internet Society (ISOC) is an international nonprofit organization founded in 1992 to promote the open development and use of the internet. It supports the technical infrastructure of the internet and advocates for internet access, freedom, and security worldwide.
ISP — Internet Service Provider
An ISP is a company that provides internet access to individuals, businesses, and organizations. When you connect to the internet at home or on your phone, you are using the services of an ISP. Popular ISPs in India include Jio, Airtel, BSNL, and ACT Fibernet.
Computer Glossary — Letters L and M
Linux
Linux is a free and open-source operating system that was created by Linus Torvalds in 1991. It is based on the Unix operating system and is known for its stability, security, and flexibility. Linux is widely used on servers, supercomputers, and Android phones. Popular Linux distributions include Ubuntu, Fedora, and Debian.
Mac OS
macOS is the operating system used on Apple Mac computers. It is known for its clean, user-friendly interface and strong security features. macOS is developed exclusively by Apple and only runs on Apple hardware. It is a popular choice among creative professionals like graphic designers, video editors, and musicians.
Modem
A modem (short for Modulator-Demodulator) is a device that converts digital data from a computer into analog signals for transmission over telephone or cable lines, and converts incoming analog signals back into digital data. Modems are used to connect computers to the internet. Modern modems often include router functionality.
MU — Memory Unit
The Memory Unit is the part of a computer system that stores data and instructions, both temporarily and permanently. It includes primary memory (RAM and ROM) and secondary memory (hard drives, SSDs). The memory unit works closely with the CPU to ensure that data is available when needed for processing.
Computer Glossary — Letters O and P
Online Processing
Online processing (also called real-time processing) is a method where data is processed immediately as it is entered, without any delay. ATM transactions, online ticket booking, and credit card processing are examples of online processing. The key feature is that results are available instantly.
Operating System
An operating system is the most important software on a computer. It acts as an interface between the user and the computer hardware, managing all resources including the processor, memory, storage, and input/output devices. Without an operating system, a computer is just hardware with no way to run programs. Examples include Windows, macOS, Linux, and Android.
Piracy
Software piracy is the illegal reproduction, distribution, or use of software without authorization from the copyright owner. It includes copying software without a license, sharing software with others, and downloading cracked versions of paid software. Software piracy is a serious crime and can result in heavy fines and legal penalties.
Primary Key
In a database, a primary key is a field (or combination of fields) that uniquely identifies each record in a table. No two records can have the same primary key value. For example, in a student database, the Roll Number could be the primary key because every student has a unique roll number.
Primary Memory
Primary memory (also called main memory) is the memory that the CPU can directly access. It includes RAM (Random Access Memory) which is temporary and ROM (Read Only Memory) which is permanent. Primary memory is much faster than secondary memory but is also more expensive. It is where the operating system and currently running programs are stored.
Computer Glossary — Letters Q and R
Query
A query is a request for specific information from a database. Queries are written in SQL (Structured Query Language) or through a graphical interface. For example, a query might ask the database to show all students who scored more than 90 marks. Queries are a powerful way to extract exactly the information you need from large databases.
Range of Cells
In Microsoft Excel, a range of cells is a group of neighboring cells that form a rectangle. A range is identified by the address of the top-left cell and the bottom-right cell, separated by a colon. For example, A1:C5 refers to all cells from A1 to C5. Ranges are used in formulas to perform calculations on multiple cells at once.
RDBMS — Relational Database Management System
An RDBMS is a type of DBMS that stores data in tables with rows and columns, and allows relationships to be established between different tables. This makes it easy to query and combine data from multiple tables. Examples include MySQL, PostgreSQL, Oracle, and Microsoft SQL Server. Most modern websites and applications use an RDBMS.
Record
In a database, a record is a complete set of information about one entity. It is made up of multiple fields. For example, in a student database, one record might contain a student’s Name, Age, Roll Number, and Grade. Records are like the rows in a database table.
Computer Glossary — Letter S
Secondary Memory
Secondary memory (also called secondary storage) is the permanent storage of a computer where data is saved even after the computer is turned off. It includes hard disk drives, SSDs, USB drives, CDs, DVDs, and memory cards. Secondary memory is slower than primary memory but can store much larger amounts of data. Learn more about storage devices on our site.
Software
Software is the set of programs, instructions, and data that tell a computer what to do. Unlike hardware (which you can touch), software is intangible. There are two main types: System software (like operating systems) manages the computer’s hardware and resources, and Application software (like MS Word or Chrome) performs specific tasks for the user.
Sorting
Sorting is the process of arranging data in a specific order — either ascending (A to Z, 1 to 100) or descending (Z to A, 100 to 1). Sorting makes it easier to find and analyze data. In Microsoft Excel, you can sort data with just a few clicks. Sorting is a fundamental operation in databases and programming.
System Software
System software is a type of software that manages and controls the computer hardware so that application software can run. It includes the operating system, device drivers, utility programs, and the BIOS. System software runs in the background and provides the foundation on which all other software runs.
Computer Glossary — Letters T and U
Tag (HTML)
In HTML, a tag is a keyword enclosed in angle brackets that defines how a web browser displays content. Tags usually come in pairs — an opening tag and a closing tag. For example, <b>Hello</b> makes the word Hello appear in bold. Tags are the building blocks of all web pages.
Unix
Unix is a powerful, multiuser, multitasking operating system developed at Bell Labs in the late 1960s. It uses a command-line interface and is known for its stability and security. Unix was very influential in the development of modern operating systems. Linux and macOS are both based on Unix principles.
UPS — Uninterruptible Power Supply
A UPS is a device that provides emergency power to a computer during a power outage. It contains a battery that automatically activates when the main power fails, giving you enough time to save your work and safely shut down the computer. A UPS also protects your computer from power surges and voltage fluctuations.
Computer Glossary — Letter V
Virus
A computer virus is a malicious program that attaches itself to legitimate files and replicates when those files are executed. Viruses can damage or delete files, slow down your computer, steal personal information, and spread to other computers. To protect yourself, always use updated antivirus software and avoid downloading files from unknown sources.
Related Articles You Should Read
Now that you have read through this complete computer glossary, here are some related articles on FixingGeek.com that will help you build on your knowledge:
- Computer Abbreviations — Complete List — Learn the full forms of all important computer abbreviations.
- Computer Hardware Guide — Understand all hardware components in detail.
- Input Devices — Complete guide to all input devices.
- Output Devices — Complete guide to all output devices.
- Storage Devices — Learn about all types of storage devices.
- Computer Basic Quiz — Test your computer knowledge with our free quiz.
- Computer Awareness — Important computer awareness points for exams.
- Supercomputer — Learn about the most powerful computers in the world.
- Mainframe Computer — Understand what mainframe computers are and how they work.
- File Extensions — Complete list of common file extensions and their meanings.
Computer Awareness — 40 Frequently Asked Questions (FAQ)
Q1. What is computer awareness? A: Basic knowledge of computers, hardware, software, internet, and technology.
Q2. What does CPU stand for? A: Central Processing Unit.
Q3. What is RAM? A: Random Access Memory — temporary memory used while the computer is running.
Q4. What is ROM? A: Read Only Memory — permanent memory that stores startup instructions.
Q5. What is the brain of a computer? A: CPU (Central Processing Unit).
Q6. What is an operating system? A: Software that manages all hardware and software on a computer.
Q7. Name three popular operating systems. A: Windows, macOS, Linux.
Q8. What is a supercomputer? A: The fastest and most powerful type of computer used for complex calculations.
Q9. Which generation of computers used vacuum tubes? A: First Generation (1940–1956).
Q10. Which generation of computers used transistors? A: Second Generation (1956–1963).
Q11. What is a motherboard? A: The main circuit board that connects all components of a computer.
Q12. What is the difference between HDD and SSD? A: HDD uses moving parts and is slower. SSD has no moving parts and is faster.
Q13. What is 1 Byte equal to? A: 8 Bits.
Q14. How many KB make 1 MB? A: 1024 KB = 1 MB.
Q15. What is a LAN? A: Local Area Network — a network within a small area like a home or office.
Q16. What is a WAN? A: Wide Area Network — a network covering a large geographical area.
Q17. Who invented the World Wide Web? A: Tim Berners-Lee in 1989.
Q18. What does HTTP stand for? A: HyperText Transfer Protocol.
Q19. What does URL stand for? A: Uniform Resource Locator.
Q20. What is a firewall? A: A security system that monitors and controls network traffic to block unauthorized access.
Q21. What is a computer virus? A: A malicious program that copies itself and damages files on a computer.
Q22. What is phishing? A: A trick used by hackers to steal passwords or bank details through fake websites or emails.
Q23. What is encryption? A: Converting data into a coded format so only authorized users can read it.
Q24. What does USB stand for? A: Universal Serial Bus.
Q25. What does PDF stand for? A: Portable Document Format.
Q26. What is GUI? A: Graphical User Interface — allows users to interact with computers using icons and menus.
Q27. What is the default file extension of MS Word? A: .docx
Q28. What is the default file extension of MS Excel? A: .xlsx
Q29. What key starts a PowerPoint slideshow? A: F5.
Q30. What is cloud storage? A: Storing data on remote servers accessible via the internet. Example: Google Drive.
Q31. What is an input device? Give one example. A: A device that sends data to the computer. Example: Keyboard.
Q32. What is an output device? Give one example. A: A device that receives data from the computer. Example: Monitor.
Q33. What does DNS stand for? A: Domain Name System.
Q34. What is a router? A: A device that connects multiple networks and directs data between them.
Q35. What does Wi-Fi stand for? A: Wireless Fidelity.
Q36. What is malware? A: Any malicious software designed to damage or gain unauthorized access to a computer.
Q37. What does VPN stand for? A: Virtual Private Network.
Q38. What is the shortcut to permanently delete a file? A: Shift + Delete.
Q39. What does BIOS stand for? A: Basic Input Output System.
Q40. What is IoT? A: Internet of Things — everyday devices connected to the internet to send and receive data.
Conclusion
This complete computer glossary covers all the important computer terms from A to Z that every student, job seeker, and computer user should know. Understanding these terms will help you perform better in exams, crack job interviews, communicate more effectively at work, and use computers with much greater confidence.
At FixingGeek.com, our goal is to make technology simple and understandable for everyone. Bookmark this computer glossary page and come back whenever you need a quick definition. If you found this article helpful, please share it with your friends, classmates, and colleagues who might also benefit from it.
Thank you for reading. Stay tuned with FixingGeek and feel free to comment below if you have any questions or if you want us to add more terms to this glossary. We are always happy to help!
