Extreme Rules is an annual paid professional wrestling event of WWE. The name of the event derives from the homonymous term used by WWE to refer to matches played under the rules of hardcore wrestling. The defunct Extreme Championship Wrestling federation originally used the term to describe the stipulations of all of its matches.
The event saw the light in 2009, however the idea was already born with the One Night Stand pay-per-view, its predecessor, made since 2005 as a tribute to the old ECW, purchased by WWE a few years earlier. The 2008 edition of One Night Stand was subtitled Extreme Rules, and the following year that subtitle became the show's new name. In 2009, WWE changed the pay-per-view schedule, placing it after WrestleMania.
WWE maintained continuity between the two events until 2010, inserting the Extreme Rules PPVs in the One Night Stand chronology. Despite this, shortly after the 2010 edition took place, the federation recognized the 2009 edition as the first event in the history of pay-per-view.
In 2017, Extreme Rules was assigned as a Raw roster exclusive. However, in 2018 the event became accessible for athletes on both rosters and takes place in July. In 2020 the edition was called The Horror Show at Extreme Rules. In 2021 It has since been indicated that the 2021 event will be held in October.