The set union operation is denoted using the cup symbol. The union of two sets returns the combined elements of both sets where duplicates are ignored. For example, the union of the two sets below is shown.

For example, the union of the two sets A and B is denoted as:

If A = { w, x, y} and B = { x, y, z} then the union operator returns the combined elements in both sets. Since is a set is defined as a unique collection of elements, elements are not duplicated.