1896 was a leap year but 1900 was not

1896 was a leap year but 1900 was not a leap year even though they are both divisible by 4.

In order for a century to be a leap year it must be divisible by 400, therefore 2000 was a leap year but the year 2100 is not a leap year. 2100 is divisible by 4 but it is not divisible by 400.