ELI5: Explain Like I'm 5

Category of groups

Okay, let's imagine that you have a bunch of toys like cars, dolls, and blocks. You might want to put them into groups based on what they are - like all the cars together in one group, all the dolls in another, and all the blocks in a third group.

Now, imagine that instead of toys, we have mathematical objects called groups. Just like toys, groups can be different from each other, but they share some common features. We might want to group them together based on those features, and this is what we call a category.

A category of groups means that we are putting groups into groups based on some common features. For example, we might group together all the groups that have a special property called "abelian" (which just means that you can swap two group elements and the result is the same). Or we might group together all the groups that are related to each other in a certain way.

By studying these categories of groups, we can learn more about the properties of individual groups and how they relate to each other. It's like sorting your toys into groups - it helps you understand more about each toy and how it is similar or different from others.