WWE's original "Big Four" pay-per-view events are WrestleMania, Royal Rumble, Survivor Series, and SummerSlam.
These events have been held annually since the 1980s and are considered the most prestigious and important events in WWE's calendar.
WrestleMania, which began in 1985, is the biggest event of the year and often features the most high-profile matches and celebrity appearances.
The Royal Rumble, which began in 1988, features a 30-man battle royal match where the winner earns a championship match at WrestleMania.
Survivor Series, which began in 1987, originally featured team-based elimination matches but has since evolved to include singles matches as well.
SummerSlam, which began in 1988, is often referred to as WWE's second biggest event of the year and features a mix of high-profile matches and celebrity appearances.