A nonzero number is any number that is not equal to zero. This includes both positive and negative numbers as well as fractions and irrational numbers.
Numbers are categorized into different groups according to their properties. The natural numbers include all the positive counting numbers from one to infinity. The whole numbers are the same as the natural numbers but include zero. The integers are all the whole numbers and all the negative counting numbers.
The rational numbers are all the numbers that can be expressed as a fraction, which means putting an integer over a nonzero integer. The irrational numbers, such as pi, are those that cannot be expressed as fractions because they do not terminate. Finally, the set of real numbers encompasses all the rational and irrational numbers.