Before you understand what Irrational Numbers are, you are advised to read:
What are Rational Numbers ?
What are Integers ?
An irrational number is the one which cannot be expressed in the form of p/q .
For example:
√ 2 , √ 3 , √ 5 , √ 6 , √ 11
There are infinite Irrational Numbers.
Π  (pie) is also known as an irrational number
