Natural numbers are all the numbers from 1 onwards, i.e., 1, 2, 3, 4, 5, ………… and are used for counting.
We know since our childhood we are using numbers 1, 2, 3, 4, 5, 6, ……….. to count and calculate.
For example: 3 apples, 7 mangoes, 2 balls,etc.
Here, apples, mangoes, balls, etc. are objects whereas three, seven, two, etc. indicate about the quantities of these objects.
When we count objects in a group of objects, we are counting from one and then go on to two, three, four etc. This is a natural way of counting objects.
Hence, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, …..….. are called natural numbers.
Since, we start counting with number 1, so 1 is the first natural number. If we add 1 to the first natural number 1, then we get 2, the second natural number. By adding 1 to 2, we get 3, the third natural number. In fact, by adding 1 to any natural number we get the next natural number.
It follows from the above discussion that 1 is the first natural number and there is no last natural number.
Thus, if we start counting natural numbers, we cannot complete the counting of all natural numbers even if we continue to count day and night for our whole life. This fact is expressed by saying that there are infinitely many natural numbers.