Computer Science Study Notes
Harvard-Style Beginner Guide (2026 Edition)
Introduction to Computer Science
Computer Science is the study of computers, software, algorithms, AI, cybersecurity,
networking, and programming.
Computer Hardware Basics
Main components include CPU, RAM, storage devices, input devices, and output devices.
Software Basics
System software controls the computer while application software helps users perform
tasks.
Binary Numbers
Computers understand binary numbers using only 0 and 1.
Programming Fundamentals
Programming is writing instructions for computers using languages such as Python,
JavaScript, C++, and Java.
Algorithms
Algorithms are step-by-step instructions used to solve problems efficiently.
Data Structures
Common data structures include arrays, stacks, queues, and linked lists.
Web Development
Frontend uses HTML, CSS, and JavaScript while backend uses Python, PHP, or Node.js.
Databases
Databases store organized information using systems like MySQL, PostgreSQL, MongoDB,
and SQLite.
Networking Fundamentals
Networking connects computers together through routers, Wi‑Fi, IP addresses, and the
internet.
Cybersecurity Basics
Cybersecurity protects systems against malware, phishing, hacking, and viruses.
Artificial Intelligence Basics
AI enables machines to simulate intelligence. Examples include ChatGPT and virtual
assistants.
Python Programming Notes
Example:
print("Hello World")
for i in range(5):
print(i)
HTML Basics
Example:
<!DOCTYPE html>
<html>
<head>
<title>My Website</title>
</head>
<body>
<h1>Hello</h1>
</body>
</html>
JavaScript Basics
Example:
let name = "Nova";
console.log(name);
Practice Projects
Build projects such as calculators, websites, chatbots, weather apps, and portfolio sites.
Free Harvard Resources
Harvard CS50: https://cs50.harvard.edu
Harvard Free Courses: https://pll.harvard.edu/catalog/free
MIT OpenCourseWare: https://ocw.mit.edu
freeCodeCamp: https://www.freecodecamp.org
Recommended Study Plan
Month 1: Computer basics and Python
Month 2: Algorithms and web development
Month 3: Databases and networking
Month 4: AI and building projects
Final Advice
Practice consistently, build projects, solve problems daily, and continue learning through
experimentation.