**Rational numbers** are numbers which can be written as fractions in the form p/q, where p and q are integers and q is not zero:

-5, 2, ¼, ½, 0.75, 1000, 0 .....

When written as decimals, rational numbers either terminate or recur.

**Irrational numbers **are numbers which cannot be written as fractions:

√2, √5, π, 1 + √2, _{3}√2

When written as decimals, irrational numbers do not terminate or recur.

They go on for ever without repeating themselves.