These sites offer thousands of free online classes on just about everything

Love is a strange thing. For instance, I love my three young children. On the other hand, I also love when they go back to school each fall.

I also, in my mid-forties, still love learning. So about this time each year, as all the kids are heading back to class, I get inspired myself to go back to school, as it were—from the comfort of my desk.

In that spirit, here’s a shortlist of thousands of free online courses from some of the big-name education waypoints around the web. You’ll find everything from straightforward college courses to professional development to learning new hobbies.

EdX: 3,600+ free courses

If you can’t find a learning experience for free on EdX, it probably doesn’t exist. The site’s raison d’être: serving up online courses from top colleges and universities around the world, almost all of which can be audited at no cost.

That’s the catch, though it’s a small one. Auditing a course means you miss out on tests, quizzes, and certain course materials. However, you can pay in order to get real-life course credit. Course costs can run into the thousands, just like real-life school. But if you’re looking to absorb and retain material, and don’t mind not be tested on it, this is a great place to start.

Coursera: 2,500+ free courses

Coursera is similar to EdX, although it does have a dedicated free courses section. Compared to EdX, Coursera skews a bit more toward professional training, but it’s likely you’ll be able to find a fair amount of overlap if you look hard enough.

That being said, give Coursera a shot if you’re looking to do a bit of professional development in your spare time.

Codecademy: 100+ free coding courses

Looking to try your hand at programming? Spin up a free Codecademy account.

Then, on its catalog page, scroll down to the “Most popular courses” section and filter the dropdown submenu to select free courses.

That’s a good place to start, although there’s no overarching free section that shows you every single freebie. But once you find a coding discipline that really speaks to you, you can drill into it from the left-hand nav and filter free courses similarly.

Udemy: 500+ free courses

Last stop: Udemy’s free courses section. Here you’ll find a nice mix of professional development, coding classes, and classes that teach you new skills, such as how to take better photos or learn a particular software product.

If you’re interested in real-world learning from people working inside various industries—not necessarily professors, in other words—then you’ll likely find what you’re looking for here. You can even sign up to teach classes yourself if you’re an expert in your field.