Two sets are equal if and only if they have the same elements.

The order of elements in a set does not matter.

{3, 1, 4, 2} = {1, 2, 3, 4}

Here are some frequently seen sets:

N = {0, 1, 2, 3, ...}Natural Numbers
Z = {..., −3, −2, −1, 0, 1, 2, 3, ...}Integers
R = { x | x is a real number}Real Numbers