ELI5: Explain Like I'm 5

Algebra (ring theory)

Okay kiddo, are you ready to learn about algebra and ring theory? Here we go!

Imagine you have a group of things, like five apples. You can add more apples to the group, or take some away. This is what we call addition, and it's something you already know how to do! Now let's say you want to take groups of apples and multiply them. If you have two groups of three apples each, you can multiply them to get six apples in total. This is what we call multiplication.

When we talk about algebra, we're basically talking about using numbers (or other things, like mathematical expressions or functions) to represent those apples we were just talking about. We can add them together or multiply them, just like the apples.

But what is ring theory? A ring is basically like a special kind of algebra. In a ring, you have two operations: addition and multiplication, just like before. But the rules for these operations are a bit different. For example, in a ring, multiplication doesn't always work the same way as it does with regular numbers. If you multiply two numbers in a ring, you might not always get a third number back.

In a ring, there are some special properties that the operations have to follow. One of these is called the distributive property, which basically means that when you multiply two numbers and then add them to another number, it's the same as adding those two numbers first and then multiplying them. This can be a bit confusing at first, but it's an important one to remember.

Another thing that's cool about rings is that they can have something called a "unit". This is basically a special number that behaves a bit like one. If you multiply any number in the ring by the unit, you get back the same number.

So there you have it, kiddo! Algebra and ring theory are all about using numbers (or other things) to represent things we can add and multiply, and following some special rules to make sure everything works properly. With a little practice, you'll be a math whiz in no time!