Suppose D is the set of all players of cricket team and E is the set of all players of hockey team, of your school. some players may be common to both the terms. School wants to be felicitate these players in a function. when all the members are called, you see that the collection consists of all players who are either in cricket team or in hockey team. this is precisely the idea of union of sets.

Suppose A and B are two sets. The union of the sets A and B is the set of all those elements which belong to B. It is denoted by AUB(read as A union B). Thus, AUB = {x |x ∈ A or x ∈ B} Example:

If A = {1, 2, 4, 5} and B = {2, 4, 6, 8, 10} then AUB = {1, 2, 4, 5, 6, 8, 10}

We can represent the union of two sets using the Venn diagram. In the adjacent figure. A = {x, z} ; b = {y, z }{ and AUB = {x , y, z} the sets A and B are represented by circles. The shaded portion represents AB.