In the history of Ireland, Gaelic sports were connected with cultural nationalism. Until the mid-20th century a person could have been banned from playing Gaelic football, hurling, or other sports administered by the Gaelic Athletic Association (GAA) if she/he played or supported Association football, or other games seen to be of British origin. Until recently the GAA continued to ban the playing of football and rugby union at Gaelic venues. This ban, also known as Rule 42, is still enforced, but was modified to allow football and rugby to be played in Croke Park while Lansdowne Road was redeveloped into Aviva Stadium. Until recently, under Rule 21, the GAA also banned members of the British security forces and members of the RUC from playing Gaelic games, but the advent of the Good Friday Agreement in 1998 led to the eventual removal of the ban.
Sports science is a widespread academic discipline, and can be applied to areas including athlete performance, such as the use of video analysis to fine-tune technique, or to equipment, such as improved running shoes or competitive swimwear. Sports engineering emerged as a discipline in 1998 with an increasing focus not just on materials design but also the use of technology in sport, from analytics and big data to wearable technology. In order to control the impact of technology on fair play, governing bodies frequently have specific rules that are set to control the impact of technical advantage between participants. For example, in 2010, full-body, non-textile swimsuits were banned by FINA, as they were enhancing swimmers' performances.
In the United States, the championship game of the NFL, the Super Bowl, has become one of the most watched television broadcasts of the year. Super Bowl Sunday is a de facto national holiday in America; the viewership being so great that in 2015, advertising space was reported as being sold at $4.5m for a 30-second slot.
Popularity in 2018 of major sports by size of fan base: