Mathematically, generally speaking, the intersection of two given sets A and B refers to a set that contains all elements belonging to both A and B, but does not contain other elements.

The intersection of a and b is written as "A ∩B" Formally: x ∈ A ∩B if and only if x ∈ A and x ∈ b.

For example, the intersection of sets A = {1, 2,3} and B = {2 2,3,4} is {2,3}. Let's write it down as a ∩ b = {2 2,3}.

To put it bluntly, it is the common part of the two sets.