Following the success of WrestleMania I in 1985, a second WrestleMania was scheduled for 1986. WrestleMania would become considered the World Wrestling Federation's (WWF, now WWE) flagship event. It is held annually between mid-March to mid-April. Following the advent of Survivor Series in 1987 and then Royal Rumble and SummerSlam in 1988—WWF's four original pay-per-views—the four would eventually be dubbed the "Big Four". WrestleMania would eventually be described as the Super Bowl of sports entertainment.