50 Computer Science Quiz Questions & Answers

Below are 50 computer science quiz questions with the correct answer and a short explanation for each. Use them to revise, host a quiz night, or prepare for competitions — then challenge yourself with the timed, interactive version on QuizOxa.

Computer Science Quiz Questions and Answers

Q1. What does CPU stand for?

✅ Answer: Central Processing Unit

💡 The CPU (Central Processing Unit) is the 'brain' of the computer that executes instructions and performs calculations.

Q2. What does HTML stand for?

✅ Answer: Hyper Text Markup Language

💡 HTML (Hyper Text Markup Language) is the standard markup language for creating web pages and web applications.

Q3. What is an algorithm?

✅ Answer: A step-by-step procedure to solve a problem

💡 An algorithm is a finite sequence of well-defined instructions for solving a problem or performing a computation.

Q4. What is RAM?

✅ Answer: Random Access Memory

💡 RAM (Random Access Memory) is volatile memory that temporarily stores data the CPU is actively using for quick access.

Q5. Who is considered the 'father of computer science'?

✅ Answer: Alan Turing

💡 Alan Turing is considered the father of computer science for his foundational work on computation theory and the Turing machine concept.

Q6. What is binary code?

✅ Answer: A system using only 0s and 1s

💡 Binary code is the fundamental language of computers, using only two digits (0 and 1) to represent all data and instructions.

Q7. What does URL stand for?

✅ Answer: Uniform Resource Locator

💡 URL (Uniform Resource Locator) is the address of a web resource on the internet, like https://www.quizoxa.com.

Q8. What is a bug in programming?

✅ Answer: An error or flaw in code

💡 A bug is an error, flaw, or unintended behavior in a computer program. The term dates back to a moth found in a Harvard computer in 1947.

Q9. What programming language is known for web development?

✅ Answer: JavaScript

💡 JavaScript is the primary language for web development, running in browsers to create interactive websites and web applications.

Q10. What is an operating system?

✅ Answer: Software that manages computer hardware and software

💡 An operating system (OS) like Windows, macOS, or Linux manages hardware, software, and provides services for computer programs.

Q11. What does 'AI' stand for?

✅ Answer: Artificial Intelligence

💡 AI (Artificial Intelligence) refers to computer systems designed to perform tasks that normally require human intelligence.

Q12. What is Python primarily known for?

✅ Answer: Easy readability and versatility

💡 Python is known for its clean, readable syntax and versatility — used in AI, data science, web development, and automation.

Q13. What is a database?

✅ Answer: An organized collection of structured data

💡 A database is an organized collection of structured data stored electronically, managed by a Database Management System (DBMS).

Q14. What does 'API' stand for?

✅ Answer: Application Programming Interface

💡 An API (Application Programming Interface) allows different software applications to communicate with each other.

Q15. What is cloud computing?

✅ Answer: Delivering computing services over the internet

💡 Cloud computing delivers computing services (servers, storage, databases, networking) over the internet ('the cloud') on demand.

Q16. What is the difference between HTTP and HTTPS?

✅ Answer: HTTPS is encrypted and secure

💡 HTTPS adds SSL/TLS encryption to HTTP, securing data transferred between browser and server — essential for passwords and payments.

Q17. What is machine learning?

✅ Answer: A subset of AI where systems learn from data

💡 Machine learning is a branch of AI where algorithms learn patterns from data and improve performance without being explicitly programmed.

Q18. What is a 'firewall' in computing?

✅ Answer: A security system monitoring network traffic

💡 A firewall is a network security system that monitors and controls incoming and outgoing traffic based on predetermined security rules.

Q19. What does SSD stand for?

✅ Answer: Solid State Drive

💡 An SSD (Solid State Drive) uses flash memory to store data, much faster than traditional HDDs with no moving mechanical parts.

Q20. Who created the World Wide Web?

✅ Answer: Tim Berners-Lee

💡 Tim Berners-Lee invented the World Wide Web in 1989 at CERN, creating HTML, HTTP, and the first web browser.

Q21. What is Git used for?

✅ Answer: Version control for code

💡 Git is a distributed version control system that tracks changes in source code, allowing multiple developers to collaborate on projects.

Q22. What is a 'stack overflow' error?

✅ Answer: When call stack memory is exhausted

💡 A stack overflow occurs when the call stack exceeds its allocated memory, usually due to infinite recursion or very deep function calls.

Q23. What is Big O notation used for?

✅ Answer: Describing algorithm efficiency and time complexity

💡 Big O notation describes the worst-case time or space complexity of an algorithm, e.g., O(n) for linear time, O(log n) for logarithmic.

Q24. What is a 'linked list' in data structures?

✅ Answer: Nodes connected by pointers

💡 A linked list is a linear data structure where each element (node) contains data and a pointer/reference to the next node in the sequence.

Q25. What language is used for iOS app development?

✅ Answer: Swift

💡 Swift is Apple's programming language for iOS, macOS, watchOS, and tvOS app development, introduced in 2014 as a successor to Objective-C.

Q26. What is recursion in programming?

✅ Answer: A function that calls itself

💡 Recursion is when a function calls itself to solve a problem by breaking it into smaller subproblems until reaching a base case.

Q27. What is the purpose of CSS?

✅ Answer: Styling web pages

💡 CSS (Cascading Style Sheets) is used to style and layout web pages — controlling colors, fonts, spacing, and responsive design.

Q28. What is Docker used for?

✅ Answer: Containerization of applications

💡 Docker is a platform that packages applications into containers — lightweight, portable, self-sufficient environments that run consistently everywhere.

Q29. What is SQL used for?

✅ Answer: Managing and querying relational databases

💡 SQL (Structured Query Language) is the standard language for managing and querying relational databases like MySQL, PostgreSQL, and Oracle.

Q30. What does 'open source' mean?

✅ Answer: Source code publicly available for anyone to use and modify

💡 Open source software has publicly available source code that anyone can inspect, modify, and distribute. Examples include Linux, Firefox, and Python.

Q31. What is blockchain in simple terms?

✅ Answer: A decentralized, tamper-proof digital ledger

💡 Blockchain is a chain of blocks containing data, linked cryptographically. Once data is recorded, it's extremely difficult to change.

Q32. What is a compiler?

✅ Answer: Software that translates code into machine language

💡 A compiler translates the entire source code of a program into machine code (binary) before execution, unlike an interpreter which does it line by line.

Q33. What is the Internet of Things (IoT)?

✅ Answer: Network of physical devices connected to the internet

💡 IoT refers to physical devices (sensors, appliances, vehicles) connected to the internet, collecting and sharing data automatically.

Q34. What is cybersecurity?

✅ Answer: Protecting systems and networks from digital attacks

💡 Cybersecurity involves protecting computers, servers, networks, and data from malicious attacks, unauthorized access, and digital threats.

Q35. What does 'debugging' mean?

✅ Answer: Finding and fixing errors in code

💡 Debugging is the process of identifying, isolating, and fixing bugs (errors) in computer programs to ensure correct functionality.

Q36. What is a 'hash table'?

✅ Answer: A data structure for fast key-value lookups

💡 A hash table stores key-value pairs using a hash function for fast O(1) average-time lookups, insertions, and deletions.

Q37. Which company developed the Android operating system?

✅ Answer: Google

💡 Android was originally developed by Android Inc., acquired by Google in 2005. It's now the world's most popular mobile OS.

Q38. What is React.js?

✅ Answer: A JavaScript library for building user interfaces

💡 React.js is a JavaScript library developed by Facebook (Meta) for building fast, interactive user interfaces, especially single-page applications.

Q39. What is a VPN?

✅ Answer: Virtual Private Network

💡 A VPN (Virtual Private Network) creates an encrypted tunnel for your internet traffic, protecting privacy and allowing access to restricted content.

Q40. What does 'IP address' stand for?

✅ Answer: Internet Protocol address

💡 An IP (Internet Protocol) address is a unique numerical identifier assigned to each device connected to a computer network.

Q41. What is quantum computing?

✅ Answer: Computing using quantum-mechanical phenomena

💡 Quantum computing uses quantum bits (qubits) that can exist in multiple states simultaneously, potentially solving problems impossible for classical computers.

Q42. What programming language is used for Android app development?

✅ Answer: Kotlin/Java

💡 Kotlin (and Java) are the primary languages for Android development. Google declared Kotlin the preferred language in 2019.

Q43. What is 'DevOps'?

✅ Answer: Practices combining development and operations

💡 DevOps is a set of practices combining software development (Dev) and IT operations (Ops) to shorten the development lifecycle and deliver updates faster.

Q44. What is the difference between frontend and backend?

✅ Answer: Frontend is user-facing; backend is server-side logic

💡 Frontend handles the user interface (HTML, CSS, JS); backend handles server logic, databases, and APIs (Node.js, Python, etc.).

Q45. What is a 'DDoS attack'?

✅ Answer: Overwhelming a system with traffic to make it unavailable

💡 A DDoS (Distributed Denial of Service) attack floods a server with massive traffic from multiple sources, making it unavailable to legitimate users.

Q46. What is Node.js?

✅ Answer: A JavaScript runtime for server-side development

💡 Node.js is a JavaScript runtime built on Chrome's V8 engine, allowing JavaScript to run on servers — enabling full-stack JavaScript development.

Q47. What is the Turing Test?

✅ Answer: A test to determine if a machine can exhibit human-like intelligence

💡 The Turing Test, proposed by Alan Turing in 1950, tests a machine's ability to exhibit intelligent behavior indistinguishable from a human.

Q48. What is an IDE?

✅ Answer: Integrated Development Environment

💡 An IDE (Integrated Development Environment) is software providing tools for coding: editor, debugger, compiler, and more (e.g., VS Code, IntelliJ).

Q49. What is ChatGPT?

✅ Answer: An AI language model by OpenAI

💡 ChatGPT is an AI chatbot developed by OpenAI, using large language models (GPT) to generate human-like text responses.

Q50. What is the Linux operating system?

✅ Answer: An open-source Unix-like operating system

💡 Linux is a free, open-source operating system kernel created by Linus Torvalds in 1991. It powers most servers, Android phones, and supercomputers.

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