Throwback uniforms, throwback jerseys (AmE) or retro kits (BrE) or heritage guernseys (AuE) are sports uniforms styled to resemble the uniforms that a team wore in the past. One-time or limited-time retro uniforms are sometimes produced to be worn by teams in games, on special occasions such as anniversaries of significant events.
Throwback uniforms have proven popular in all major pro and college sports in North America, not only with fans, but with the teams' merchandising departments. Because the "authentic" uniforms (accurate reproductions) and less-authentic "replicas" had been so popular at retail, the professional leagues institutionalized throwbacks as "third jerseys".
Throwbacks were first popularized in Major League Baseball, where teams not only wore renditions of their past styles, but also tributes to defunct minor league and Negro League baseball teams as well. Often, the games where teams will wear throwbacks are promoted as "Turn Back The Clock Nights". Throwbacks also make frequent appearances every season in college football games, National Hockey League games, and in National Basketball Association games.
The first companies to produce throwback uniforms were Tiedman & Company Sportswear (college football, basketball, hockey, NFL and World Cup soccer), Mitchell & Ness (Major League Baseball), and Ebbets Field Flannels (Negro League baseball). All three companies are still in business; Tiedman & Company relaunched in 2009 under the brand name Tiedman & Formby Vintage Athletic Co..
In some instances, teams will wear "fauxbacks": retro designed uniforms harkening back to an era which pre-dates the team itself. For example, the Tampa Bay Rays, formed in 1998, wore 1979-style baseball uniforms in 2012, and the Dallas Mavericks have used a 1970s-like basketball uniform since 2004, despite having been established in 1980.