ELI5: Explain Like I'm 5

Ring theory

Ring theory is a type of math which deals with things called "rings". But don't worry, these aren't the kind of rings you wear on your fingers!

A ring is like a special type of box that you can put numbers inside, and then do different operations with those numbers. One of the most important things you can do with numbers inside a ring is called "addition". This is when you take two numbers and put them together to get a new number. For example, if you have the numbers 2 and 3 inside a ring, you can add them together and get the number 5.

But there's also another operation you can do with numbers in a ring, called "multiplication". This is when you take two numbers and "times" them together to get a new number. For example, if you have the numbers 2 and 3 inside a ring, you can multiply them together and get the number 6.

But not all rings are the same! Some rings have special properties that make them different from other rings. For example, some rings are "commutative", which means that the order you do the operations in doesn't matter. In other words, it doesn't matter if you add 2 and 3 and then multiply by 4, or if you multiply 2 and 3 and then add 4 – you'll end up with the same answer either way.

Other rings have even more properties, like having a special number inside them called "zero", which you can add or multiply any other number by and still get the same number back. And some rings even have what's called "inverses", which means that you can "undo" a multiplication by dividing by another number inside the ring.

Ring theory is all about studying these different types of rings and their properties, and figuring out what kinds of things you can do with them. It's kind of like playing with different types of boxes and seeing what you can put inside them and how different operations work on those things.