Union: refers to a set consisting of all elements of different sets, with the symbol ∨.

Intersection means that two sets are composed of elements belonging to the same two groups, and the symbol is ∩.

Both union and intersection satisfy the commutative law and distributive law.

The nature of union and intersection is generally very important in the learning process, which requires students to master and use it skillfully.

take for example

The nature of intersection is A∩A=A, A∩B=B∩A and so on.

The nature of union is A∪A=A, A∪? =A, A∪B=B∪A and so on.

If A∩B=A, then A∈B, and vice versa;

If A∪B=B, then A∈B, and vice versa.

If x∈(A∩B), then x∈A, x ∈ b;

If x∈(A∪B), then x∈A, or x ∈ b.