CS50x 2025: Harvard's Introduction to Computer Science

About this course

Harvard University's famous introduction to computer science and programming, taught by David J. Malan. Starting from Scratch and moving through C, Python, SQL and web development, the 2025 lectures teach you to think algorithmically and solve problems efficiently. Who it's for: complete beginners who want a rigorous first course in computer science; no prior programming needed. These are the free, official videos of the "CS50x 2025 Lectures" playlist from the CS50 YouTube channel (youtube.com/@cs50). All videos belong to Harvard University's CS50; Sikhami is not affiliated with Harvard University's CS50 and simply arranges the public playlist into a course, so you can learn one lesson at a time and keep track of your progress.

What you will learn

• Computational thinking with Scratch, then programming in C • Arrays, algorithms (searching and sorting) and how to measure their running time • Memory, pointers and data structures such as linked lists, trees and hash tables • Python for writing programs quickly • SQL and how databases store and query data • HTML, CSS and JavaScript, and building a web app with Flask • An introduction to artificial intelligence

Course content

1 section · 13 lectures · 26h 22m

1. 1. CS50x 2025 Lectures

   • CS50x 2025 - Introduction1m
   • CS50x 2025 - Lecture 0 - Scratch1h 58m
   • CS50x 2025 - Lecture 1 - C2h 34m
   • CS50x 2025 - Lecture 2 - Arrays2h 10m
   • CS50x 2025 - Lecture 3 - Algorithms2h 6m
   • CS50x 2025 - Lecture 4 - Memory2h 26m
   • CS50x 2025 - Lecture 5 - Data Structures2h 3m
   • CS50x 2025 - Lecture 6 - Python2h 11m
   • CS50x 2025 - Artificial Intelligence56m
   • CS50x 2025 - Lecture 7 - SQL2h 37m
   • CS50x 2025 - Lecture 8 - HTML, CSS, JavaScript3h 14m
   • CS50x 2025 - Lecture 9 - Flask3h 3m
   • CS50x 2025 - Lecture 10 - The End57m