An overview of CS50P, Harvard’s Introduction to Python, and your path to a free certificate .

Although Class Central lists online courses in 87 languages, courses made in English outnumber all of the others by more than six to one. English is therefore a useful language to know, even though some courses have subtitles in a range of languages. Earlier this year, we updated our list of courses to help improve your writing skills. These courses all assume some fluency in the language. But what if you do not know any English, or your English is very poor? If you do not have convenient acce

Here are the best free online courses to learn OCaml, a general-purpose, statically-typed programming language that is widely used in academia and research institutions.

In Q4 2025, Duolingo announced it would let go of $50M in bookings to reach 100 million daily active users (DAUs) by 2028; a strategy Class Central covered in detail last month.  2026 is its “investment year,” and Q1 was the first quarter of execution. So far, the plan seems to be working. The Expected Results: Low Bookings, High DAUs Duolingo is running multiple tests to improve the free experience: spoken tokens for speaking practice, Speaking Adventures for real-world conversations, and fla