1. Non negative integer, also known as natural number, refers to the number used to measure the number of things or to indicate the order of things. That is, the number represented by the digits 0, 1, 2, 3, 4. Natural numbers start from 0, one after another, forming an infinite collective. Natural numbers are ordered and infinite. It can be divided into even and odd numbers, composite numbers and prime numbers.
2. Non positive integers include negative integers and zeros, which are integers in non positive numbers. (For example: 0, - 9, - 85693, - 10 ^ 8).