CS50's Introduction to Computer Science (CS50x) is free on two paths. Harvard puts the entire course online at cs50.harvard.edu/x, with lectures, problem sets, and source code open to anyone and no login needed. edX hosts the identical course and adds an optional verified certificate. Our 'Go deeper' button links to the edX listing, and we earn nothing from it: we are not in edX's affiliate program. This is the broad intro, covering C, Python, SQL, and web programming, so it's the widest starting point of the CS50 family. Learn it free on Harvard's site, or use edX if you want the certificate to show you finished.
Nearly 5 million people have taken CS50x, making it edX's largest course ever (source: Fortune Education, fortune.com/education).
About This Course
Harvard's legendary CS50 introduction to computer science. Covers C, Python, SQL, JavaScript, and web programming. The most-enrolled university course in the world.
Course Details
Frequently Asked Questions
Is CS50x free?
Yes. It's free on cs50.harvard.edu/x and free to audit on edX. Only the edX verified certificate costs money.
What languages does CS50x teach?
C first, then Python and SQL, plus JavaScript with HTML and CSS for web programming near the end.
Is CS50x hard for beginners?
It's challenging but built for newcomers. The C section is the steepest part; most people get through it with the course's support and walkthroughs.
Should I take CS50x or CS50P?
CS50x is broad and spans several languages. CS50P (Introduction to Programming with Python) focuses only on Python and is gentler if Python is your goal.
Do you make money if I use the 'Go deeper' link?
No. We are not in edX's affiliate program, so nothing you do there pays us. Harvard's free site has the exact same course either way.
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