ELI5: Explain Like I'm 5

Groupoid

Okay kiddo, imagine you have a bunch of toys like blocks and you want to put them into groups based on how they're related - maybe you put all the blue blocks together, or all the blocks that are the same size.

Now imagine you have a big pile of different shapes and colors and sizes, and you want to figure out which ones can go together in groups based on some kind of rule. For example, maybe you'll group together all the blocks that have at least one flat side.

That's kind of like what a groupoid is - it's a way of organizing things into groups based on how they're related to each other. But instead of blocks, we're talking about objects or points that we want to group together.

And in a groupoid, we don't just group things based on one rule - we group them based on lots of different rules, or "maps" as the grown-ups call them. Each map tells us how one object is related to another.

So let's say we have three objects - we'll call them A, B, and C. One map might tell us that A is connected to B, and another map might tell us that B is connected to C. We can use these maps to create a groupoid that tells us that A, B, and C are all connected in some way - even though they might not all be directly connected to each other.

It's kind of like building a map of roads and highways that tells us how we can get from one place to another - except instead of roads, we're mapping out how different objects are connected to each other.

And just like we can use a map to figure out how to get from one place to another, we can use a groupoid to study how objects are related to each other in math and science. It might sound complicated, but it's really just a clever way of organizing things so we can better understand how they all fit together.