Is the FIFA world cup held in leap years?

There is no particular reason. It is just on a 4 year cycle that started in 1930, which wasn't a leap year. With the exception of 1942 and 1946, due to World War II, it has been held every 4 years since then. Leap years have other major sporting events in them that are also on 4 year cycles. It would be a bit crowded if all sports events that follow 4 year cycles were all held in leap years and it would leave the other years with less events for sports fans. So many sporting events that are on 4 year cycles, such as the FIFA World Cup, happen to be in different years.