**Union of two sets**

The*union*of two sets is everything in both sets. For example if you have the set {3,4,5} and the set {5,6,7}, then the union of these two sets is {3,4,5,6,7}. The symbol for union is a capital U. So mathematically, the above sentence would read:

U {3,4,5} {5,6,7} = {3,4,5,6,7}