We know them as "cardinals" "Cardinal numbers" or "counting numbers". We use them to count real or unreal things. Examples of cardinal numbers are 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, and so on.
1 - one
2 - two
3 - three
4 - four
5 - five
6 - six
7 - seven
8 - eight
9 - nine
10 - ten
11 - eleven
12 - twelve
13 - thirteen
14 - fourteen
15 - Fifteen
16 - sixteen
17 - seventeen
18 - eighteen
19 - nineteen
20 - twenty