0 before a non-zero integer does not have a value. Zeros are only considered digits once placed after a non-zero integer. The only whole number that begins with zero is zero itself.
In terms of writing a decimal number that is less than 1, a zero is normally used in the ones place. Example: 0.526 not .526.
Zero shows that there is no amount. It is also used as a "placeholder" so we 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.
Whole Numbers are simply the numbers 0, 1, 2, 3, 4, 5, ... (and so on). Counting Numbers are Whole Numbers, but without the zero. Because you can't "count" zero. So they are 1, 2, 3, 4, 5, ... (and so on).
Know more about the properties of 0 (zero) at Mathsisfun.com and Rapidtables.com.