For example, if A1={a,b,c},A2={c,h},A3={a,d}, then ⋃iAi=A1∪A2∪A3={a,b,c,h,d}. We can similarly define the union of infinitely many sets A1∪A2∪A3∪⋯.
The intersection of two sets A and B, denoted by A∩B, consists of all elements that are both in A and−−− B. For example, {1,2}∩{2,3}={2}. the intersection of sets A and B is shown by the shaded area using a Venn diagram. (located on the homepage)