The third Sunday in June is a day for showing appreciation for fathers and all other father figures. It is a tradition started by Mrs. Dodd of Washington who wanted to honor her father, a Civil War veteran who raised six children by himself.
She was inspired by the Mother's Day celebration. The first observance of Father's Day took place on June 19, 1910 and it became a national holiday in the US in 1966. It is also celebrated in many other countries but on different dates.