Limit (Latin: Limes - limit) is one of the most important concepts in mathematics. If the second variable, which depends on one variable, is infinitely close to the number a during the change of the first variable, then the number a is called the limit of the quantity of the second variable. Here the concept of limit depends on the idea of the process of change and infinite approximation. The exact mathematical definition of the limit was formed in the 19th century. As a result, a new method appeared in mathematics - the method of limits. The application and development of this method led to the creation of differential calculus and integral calculus, the emergence of mathematical analysis.