WrestleMania is considered World Wrestling Entertainment's (WWE) flagship event, having first been held in 1985. It is the longest-running professional wrestling event in history and is held annually between mid-March to mid-April. It was the first of WWE's original four pay-per-views, which includes Royal Rumble, SummerSlam, and Survivor Series, dubbed the "Big Four". It has been described as the Super Bowl of sports entertainment. It was the first WrestleMania promoted under the WWE name, following the company being renamed from World Wrestling Federation (WWF) to WWE in May 2002. It was also the first WrestleMania to be held under the first brand extension that began in March 2002, which split the roster between the Raw and SmackDown! brands, represented by the shows of the same name. It was also the first WrestleMania to feature the World Heavyweight Championship that was introduced for Raw in September 2002 after the WWE Undisputed Championship became exclusive to SmackDown! and renamed to the WWE Championship.