Learn · CS50 at Harvard

CourseCS50x 202612 lectures

CS50’s Introduction to Computer Science

David J. Malan · Harvard University

Start with lecture 1 At CS50 at Harvard

About

This is CS50, Harvard University’s introduction to the intellectual enterprises of computer science and the art of programming, for concentrators and non-concentrators alike, with or without prior programming experience. (Two thirds of CS50 students have never taken CS before.) This course teaches you how to solve problems, both with and without code, with an emphasis on correctness, design, and style. Topics include computational thinking, abstraction, algorithms, data structures, and computer science more generally. Problem sets inspired by the arts, humanities, social sciences, and sciences. More than teach you how to program in one language, this course teaches you how to program fundamentally and how to teach yourself new languages ultimately. The course starts with a traditional but omnipresent language called C that underlies today’s newer languages, via which you’ll learn not only about functions, variables, conditionals, loops, and more, but also about how computers themselves work underneath the hood, memory and all. The course then transitions to Python, a higher-level language that you’ll understand all the more because of C. Toward term’s end, the course introduces SQL, via which you can store data in databases, along with HTML, CSS, and JavaScript, via which you can create web and mobile apps alike. Course culminates in a final project.

Watch an introduction in English

Assista a uma introdução em português

Vea una introducción en español.

How to Take this Course

Even if you are not a student at Harvard, you are welcome to “take” this course for free via this OpenCourseWare by working your way through the course’s eleven weeks of material. For each week, follow this workflow:

flowchart TD A[Watch Lecture] --> |recommended|B[Watch Section] A --> D B --> |recommended|C[Watch Shorts] B --> D[Submit Problem Set] C --> D

And then submit the course’s final project.

To submit the course’s problem sets and final project for feedback, be sure to create…

Lectures

  1. Scratch Week 0 · Video
  2. C Week 1 · Video
  3. Arrays Week 2 · Video
  4. Algorithms Week 3 · Video
  5. Memory Week 4 · Video
  6. Data Structures Week 5 · Video
  7. Python Week 6 · Video
  8. SQL Week 7 · Video
  9. Artificial Intelligence Artificial Intelligence · Video
  10. HTML, CSS, JavaScript Week 8 · Video
  11. Flask Week 9 · Video
  12. Week 10 Week 10 · Video

Syllabus and materials

At CS50 at Harvard, as the course publishes them.

Credits and licence

Institution
Harvard University
Department
CS50
Teacher
David J. Malan
Year
2026
Level
Undergraduate
Language
English
Subjects
Computer science
Source
CS50 at Harvard
Licence
CC BY-NC-SA 4.0, as CS50 at Harvard states it. Non-commercial use only. CS50 at Harvard's terms
Attribution
CS50, Harvard University. Licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International license.
Who can watch
CS50 at Harvard gives no rating. Invisible Network shows it to Tweens profiles and older, judged from what the source says about it. How courses are placed