Finite and Infinite Sets

A finite set is one in which it is possible to list and count all the members of the set.

Example
D = {days of the week}
= {Sunday, Monday, Tuesday, Wednesday, Thursday, Friday, Saturday}
And, n(D) = 7

An infinite set is one in which it is not possible to list and count all the members of the set.

Example
E = {even numbers greater than 9}
= {10, 12, 14, …}
And, n(E) = infinite