The Definition of a Set

Easy, right?
Just think about the name.
A set. A collection of things.

Indeed, a set is nothing more than a collection of some stuff, objects, numbers, things, whatever.

Everything that will be collected, part of a set, will be an Element of that set.

To say that something is part of a set, you will use the "in" symbol:For example:
"x in A" or, "x from A"

With that, it makes perfect sense to learn about the next concept:

The Subset