Cheerleading is a sport that uses organized routines that range from 1 minute to 3 minutes made from elements of tumbling, dance, jumps, cheers, and stunting to direct spectators of events to cheer on sports teams at games and matches and/or compete at cheerleading competitions. Cheerleaders draw attention to the event and encourage audience participation. The athlete involved is called a cheerleader.

Cheerleading originates in the United States, and remains a predominantly American activity, with an estimated 1.5 million participants in all-star cheerleading. The growing presentation of the sport to a global audience has been led by the 1997 start of broadcasts of cheerleading competition by ESPN International and the worldwide release of the 2000 film Bring it On. Due in part to this recent exposure, there are now an estimated 100,000 participants scattered around the rest of the world in countries including Australia, Canada, China, Colombia, France, Japan, the Netherlands, New Zealand and the United Kingdom.

Princeton graduate Thomas Peebles introduced the idea of organized crowds cheering at football games to the University of Minnesota. However, it was not until 1898 that University of Minnesota student Johnny Campbell directed a crowd in cheering "Rah, Rah, Rah! Sku-u-mar, Hoo-Rah! Hoo-Rah! Varsity! Varsity! Varsity, Minn-e-So-Tah!”, making Campbell the very first cheerleader and November 2, 1898 the official birth date of organized cheerleading.

Cheerleading started out as an all-male activity, but females began participating in 1923, due to limited availability of female collegiate sports. At this time, gymnastics, tumbling, and megaphones were incorporated into popular cheers, and are still used today. Today it is estimated that 97% of cheerleading participants overall are female, but males still make up 50% of cheering squads at the collegiate level.

In 1948, Lawrence "Herkie" Herkimer, of Dallas, TX and a former cheerleader at Southern Methodist University formed the National Cheerleaders Association (NCA) as a way to hold cheerleading clinics. In 1949, The NCA held its first clinic in Huntsville, TX with 52 girls in attendance, "Herkie" contributed many firsts to the sport: the founding of the Cheerleader & Danz Team cheerleading uniform supply company, inventing the herkie and creating the "Spirit Stick". By the 1960s, college cheerleaders began hosting workshops across the nation, teaching fundamental cheer skills to eager high-school-age girls. In 1965, Fred Gastoff invented the vinyl pom-pon and it was introduced into competitions by the International Cheerleading Foundation (now the World Cheerleading Association or WCA). Organized cheerleading competitions began to pop up with the first ranking of the "Top Ten College Cheerleading Squads" and "Cheerleader All America" awards given out by the International Cheerleading Foundation in 1967. In 1978, America was introduced to competitive cheerleading by the first broadcast of Collegiate Cheerleading Championships on CBS.

In the 1960s National Football League (NFL) teams began to organize professional cheerleading teams. The Baltimore Colts (now the Indianapolis Colts) was the first NFL team to have an organized cheerleading squad.It was the Dallas Cowboys Cheerleaders who gained the spotlight with their revealing outfits and sophisticated dance moves, which debuted in the 1972-1973 season, but were first seen widely in Super Bowl X (1976). This caused the image of cheerleaders to permanently change, with many other NFL teams emulating them. Most of the professional teams' cheerleading squads would more accurately be described as dance teams by today's standards; as they rarely, if ever, actively encourage crowd noise or perform modern cheerleading moves.

The 1980s saw the onset of modern cheerleading with more difficult stunt sequences and gymnastics being incorporated into routines. ESPN first broadcasted the National High School Cheerleading Competition nationwide in 1983.

Cheerleading organizations such as the American Association of Cheerleading Coaches and Advisors (AACCA), founded in 1987, started applying universal safety standards to decrease the number of injuries and prevent dangerous stunts, pyramids and tumbling passes from being included in routines. In 2003, the National Council for Spirit Safety and Education (NCSSE) was formed to offer safety training for youth, school, all star and college coaches. The NCAA requires college cheer coaches to successfully complete a nationally recognized safety-training program. The NCSSE or AACCA certification programs are both recognized by the NCAA.

Even with its athletic and competitive development, cheerleading at the school level has retained its ties to the spirit leading traditions started back in the 1890s. Cheerleaders are seen as ambassadors for their schools, and leaders among the student body. At the college level, cheerleaders are often invited to help at university fundraisers.

Today, cheerleading is most closely associated with American football and basketball.