The union of two sets contains all the elements contained in either set (or both sets).

The union is notated A ⋃ B.

More formally, x ∊ A ⋃ B if x ∊ A or x ∊ B (or both)

The intersection of two sets contains only the elements that are in both sets.

The intersection is notated A ⋂ B.

More formally, x ∊ A ⋂ B if x ∊ A and x ∊ B

The complement of a set A contains everything that is not in the set A.

The complement is notated A’, or Ac, or sometimes ~A.