Summerfest is an annual music festival held at the 75-acre (30-hectare) Henry Maier Festival Park along the lakefront in Milwaukee, Wisconsin. The festival lasts for 11 days, is made up of 11 stages with performances from over 700 bands, and since the mid-1970s has run from late June through early July, usually including the 4th of July holiday. Summerfest attracts between 800,000 and 1,000,000 people each year, promoting itself as "The World's Largest Music Festival", a title certified by the Guinness World Records since 1999.

Summerfest is operated by a non-profit board that hires the production staff to operate both the venue and main Summerfest event, which features local and nationally known music talent from a variety of music genres. The event also provides the opportunity to sample a wide variety of food from many Milwaukee-area restaurants. Other Summerfest attractions include comedy acts, shopping vendors, fireworks (including "The Big Bang" on opening night), other special attractions, family activities, and more.