Every integer (positive, negative, or Zero) and every decimal number is a rational number.
All terminating and non-terminating but repeating (or periodic or recurring) decimals are rational numbers.
The real numbers, which are not rational, are called irrational numbers.
The square roots, cube roots, etc. of natural numbers are irrational numbers; if their exact value can not be obtained.
All non-terminating non-repeating decimals are irrational numbers.