Once upon a time, people used to count things using their fingers and toes. But then some very clever people in India and Arabia came up with a new way to count that made things a lot easier. They invented a system of numbers that used ten different symbols, 0-9, that they could use over and over again to represent all the different numbers.
This was a big deal because before this, people had to use special symbols for each different number, which made counting and math really hard.
The Hindu-Arabic numeral system, as it eventually came to be called, spread all over the world because it made life so much easier. Merchants and traders loved it because it made keeping track of money and inventory much simpler. Mathematicians and scientists loved it because it made complex calculations much more manageable.
Eventually, it became the universal system of counting that we use today. So the next time you count to ten, remember that you're using a system that was invented a long time ago by some very clever people in India and Arabia!