[Bob]

Well, it's not exactly 365.25, which is why there are leap seconds and whatnot occasionally.

That difference from the exact 365.25 is also why most 'century years' are not leap years as you might expec that they would be.

If the year is also evenly divisible by 400, then it is. The years 1700, 1800, and 1900 were not leap years but 2000 was.

[Plummz]

Yep.