Number is a basic concept in mathematics. Its functions developed in close connection with the study of quantities, this connection has been preserved to this day, since in all branches of mathematics it is necessary to use numbers and consider different quantities.

The concept of "number" has many definitions. The first scientific concept was given by Euclid, and the original idea of numbers appeared in the Stone Age, when people began to move from simple gathering of food to producing it. Numerical terms were born very hard and also very slowly came into use. Ancient man was far from abstract thinking, he came up with only a couple of concepts: "one" and "two", other quantities were indefinite for him and were denoted by one word "many." and "three" and "four". The number "seven" has long been considered the limit of knowledge. This is how the first numbers appeared, which are now called natural and serve to characterize the number of objects and the order of objects placed in a row. Any measurement is based on some quantity (volume, length, weight, etc.). The need for accurate measurements led to the fragmentation of the initial units of measure. First, they were split into 2, 3 or more parts. This is how the first concrete fractions arose. Much later, the names of concrete fractions began to denote abstract fractions. The development of trade, industry, technology, science required more and more cumbersome calculations, easier to perform using decimal fractions. Decimal fractions became widespread in the 19th century, after the metric system of measures and weights was introduced. Modern science encounters quantities of such complexity that their study requires the invention of new numbers, the introduction of which must comply with the following rule: "actions on them must be fully defined and not lead to contradictions." New number systems are needed to solve new problems or to improve already known solutions. Now there are seven generally accepted levels of generalization of numbers: natural, real, rational, vector, complex, matrix, transfinite. Some scholars propose to expand the degree of generalization of numbers to 12 levels.