CS50: Introduction to Computer Science
Harvard's introductory course, free, running from C and memory through data structures, algorithms, Python, SQL and web development. Still the best first computer science course available anywhere at any price.
Course
Other
Harvard University
10 to 12 weeks
Beginner
Free
What it is
Harvard's introduction to computer science, published free with lectures, problem sets, and an active community. It starts in C, which is a deliberate and correct choice, then moves through Python, SQL and web fundamentals.
Why starting in C matters
Beginning with a language where you manage memory yourself means you learn what a pointer is, what the stack and heap are, and what a string actually is, before a higher level language hides all of it. People who start in Python often carry that gap for years without knowing they have it.
What to expect
The problem sets are demanding and the production quality is unusually high. Complete it properly and you will have a genuine foundation rather than familiarity with a syntax.
Best for: beginners, career changers, and self taught developers who want to fill in the fundamentals they skipped.
Ready to start?
Opens on Harvard University in a new tab.
Stuck on something specific?
Writing only gets you so far. If you want an answer to your situation rather than the general case, book a session and we will work through it together. Every session is free; a few slots open each week.
Follow along
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