# Set

## well-defined mathematical collection of distinct objects / From Wikipedia, the free encyclopedia

For the Egyptian god, see Seth.

A **set** is an idea from mathematics. A set has *members* (also called *elements*). A set is defined by its members, so any two sets with the same members are the same (e.g., if set ${\mathit {X}}$ and set ${\mathit {Y}}$ have the same members, then *${\mathit {X}}={\mathit {Y}}$*).

A set cannot have the same member more than once. Membership is the only thing that matters. For example, there is no order or other difference among the members. *Anything* can be a member of a set, including sets themselves (though if a set is a member of itself, paradoxes such as Russell's paradox can happen).