Zero

The whole number between -1 and 1, with the symbol 0

Shows that there is no amount.

Example: 6 - 6 = 0 (the difference between six and six is zero)

Also useful as a "place-holder" so that you can write a numeral properly.

Example: 502 (five hundred and two) could be mistaken for 52 (fifty two) without the zero in the tens place.