How to Use the OR operator: Do a union of two sets

Wondering how to do a union of two sets using OR operator?

The union using OR operator is an easy way. Consider two sets A(-1,3) and another set of B(-2,0). Then specify these points on line by darkening the above points given. The rule of OR is that the output will be the numbers present in both the sets. Then by using this rule we get the output as set of A U B is (-2,3) That means -2 is in B set and up to 3 is A set.