Welcome

An introduction to programming using a language called Python. Learn how to read and write code as well as how to test and “debug” it. Designed for students with or without prior programming experience who’d like to learn Python specifically. Learn about functions, arguments, and return values (oh my!); variables and types; conditionals and Boolean expressions; and loops. Learn how to handle exceptions, find and fix bugs, and write unit tests; use third-party libraries; validate and extract data with regular expressions; model real-world entities with classes, objects, methods, and properties; and read and write files. Hands-on opportunities for lots of practice. Exercises inspired by real-world programming problems. No software required except for a web browser, or you can write code on your own PC or Mac.

Whereas CS50x itself focuses on computer science more generally as well as programming with C, Python, SQL, and JavaScript, this course, aka CS50P, is entirely focused on programming with Python. You can take CS50P before CS50x, during CS50x, or after CS50x. But for an introduction to computer science itself, you should still take CS50x!

Watch an introduction

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 ten weeks of material. For each week, follow this workflow:

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

And then submit the course’s final project.

To submit the course’s problem sets and final project for feedback, be sure to create an edX account, if you haven’t already. Ask questions along the way via any of the course’s communities!

If interested in a verified certificate from edX, enroll at cs50.edx.org/python instead.
If interested in a professional certificate from edX, enroll at cs50.edx.org/programs/python (for Python) or cs50.edx.org/programs/data (for Data Science) instead.

How to Teach this Course

If you are a teacher, you are welcome to adopt or adapt these materials for your own course, per the license. Additionally, we encourage teachers to participate in the CS50 Educator Workshop to learn more about CS50’s curriculum, technology, and pedagogy.