The Southern Indoor Football League (SIFL) was an indoor football league based in the Southern and Eastern United States. The most recent incarnation of the league was a consolidation of an earlier league of the same name that was formed by Thom Hager along with Dan Blum, Robert Winfrey and Dan Ryan in 2009 and the American Indoor Football Association, which traces its roots to the founding of the Atlantic Indoor Football League in 2005. The SIFL broke up into three regional leagues after the 2011 season.

Arena football is a variety of eight-man indoor gridiron football. The game is played indoors on a smaller field than American or Canadian football, designed to fit in the same surface area as a standard North American ice hockey rink, resulting in a faster and higher-scoring game that can be played on the floors of indoor arenas. The sport was invented in 1981, and patented in 1987, by Jim Foster, a former executive of the National Football League and the United States Football League. The name is trademarked by Gridiron Enterprises and had a proprietary format until its patent expired in 2007.