Integers: Whole numbers and the opposites of whole numbers.

Rational Numbers: Numbers that can be written as a fraction (or ratio) of two integers.

Irrational Numbers:  Numbers that cannot be written as a fraction of two integers and are on the number line.

Let's look at a few examples...

Fun Fact
Since integers can be written in fractional form they can also be considered rational numbers.  However, not all rational numbers can be integers!