Set-theoretic definition of natural numbers

The natural numbers are a special group of numbers. They are the numbers we use to count up from. So, 1, 2, 3, 4, 5, 6 and so on are natural numbers. The set-theoretic definition of natural numbers says that the natural numbers are the group of numbers that include 0 and all the numbers that can be made by adding 1 to it, over and over again. So 0+1=1, 1+1=2, 2+1=3, 3+1=4, and so on. So, if you add 1 to any of the natural numbers, you get a new natural number.