An annual National Football League (NFL) championship game series. This is the highest level of professional football in the United States, culminating a season that begins in the late summer of the previous calendar year. The Super Bowl normally uses Roman numerals to identify each game, rather than the year in which it is held. For example, Super Bowl I was played on January 15, 1967, following the 1966 regular season. The single exception to this rule is Super Bowl 50, which is played last February 7, 2016, following the 2015 regular season. The game was created as part of a merger agreement between the NFL and its then-rival league, the American Football League (AFL). It was agreed that the two leagues' champion teams would play in the AFL–NFL World Championship Game until the merger was to officially begin in 1970. After the merger, each league was redesignated as a "conference", and the game has since been played between the conference champions to determine the NFL's league champion. Currently, theNational Football Conference (NFC) leads the league with 26 wins to 23 wins for the American Football Conference (AFC). The Pittsburgh Steelers hold the record for Super Bowl victories with six. Super Bowl LI begins February 5th 2017.