Set
Initial Definition

Any collection of things, without regard to their order. The members (or elements) of a set could be numbers, names, shapes, etc.

Real World Example

A set of blue marbles. This set has eight elements.

Eight blue marbles
More Examples

The set of counting numbers less than seven: { 1, 2, 3, 4, 5, 6 }. This set has six elements


The set of even counting numbers less than seven: { 2, 4, 6 }. This set has three elements.


The set of even counting numbers: { 2, 4, 6, ... }, This set has an infinite numbers of elements.