### The Catsters on YouTube: “Monads”

#### Posted by John Baez

You can see all sorts of silly things on YouTube these days — from guys flying in wingsuits to math professors making mistakes converting miles to kilometers. But what about serious stuff? Can you watch math lectures on YouTube?

Can you learn category theory?

Can you, say, learn about monads?

*Yes!* Now you can!

Just try these videos from the new sensation out of Sheffield — the group that has all the British press raving — *the Catsters!*

- Monads 1: Definition of monad. Example: the monad for monoids.
- Monads 2: Examples, continued. The monad for categories.
- Monads 3: Algebras for monads.
- Monads 3a: Answers to some questions.
- Monads 4: The category of algebras of a monad.

So far it looks like the big star of the Catsters is Eugenia Cheng. However, I hear that Simon Willerton is playing a vital role behind the scenes. Maybe he’ll star in some future videos.

I hope this is the beginning of a new trend: *higher mathematics on YouTube!*

## Re: The Catsters on YouTube

Thanks for that John. We must confess that we hadn’t quite expected such publicity at this early stage. There will be more videos soon!