Hi Ashish. I use google translator and czech idnes.cz web for you:
Indeed, in our current and valid Gregorian calendar (introduced by Pope Gregory XIII in 1582), it is not strictly every four years. There are exceptions in which the gap between transmissions is eight years. These exceptions are in the round centuries, which are not multiples of 400. Thus, the years 1700, 1800, 1900, 2100, 2200 (and so on) were not or will not be leaps. For example, between 1896 and 1904, eight years passed between two February 29th. Conversely, there are direct multiples of 400, ie 1600, 2000, 2400 (and so on). This suggests that there are few people in this world who have experienced this exception in the past (most recently in 1900) and few have experienced this exception (not earlier than 2100). Feel free to teach your children that the leap year is every four years. This is true for us and for them.
Source:
https://pavelmika.blog.idnes.cz/blog.aspx?c=248669