Summerfest (also known as "The Big Gig") is a yearly music festival held at the 75-acre Henry Maier Festival Park along the lakefront in Milwaukee, Wisconsin. The festival lasts for 11 days, and since the mid-1970s has run from late June through early July, always including the 4th of July holiday. Summerfest attracts almost one million people each year. It promotes itself as "The World's Largest Music Festival," a title certified by the Guinness World Records in 1999. Summerfest is run by the non-profit Milwaukee World Festival Inc.
Summerfest features both 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 restaurants. Other Summerfest attractions include comedy acts, shopping booths, fireworks (including "The Big Bang" sponsored by US Bank on opening night), karaoke, children's activities, and more.
Live musical acts are offered on 12 stages throughout the grounds, including the 23,000-seat Marcus Amphitheater. All shows are free with an admission ticket, with the exception of headlining acts at the Marcus Amphitheater. Admission is between $8.00 and $15.00, depending on the time of day. There are typically numerous promotions for discounted or free tickets.
The inaugural Summerfest was held in July 1968 at 35 different locations throughout the city (including Milwaukee County Stadium and Milwaukee Arena), and its events ranged from concerts to a film festival, an air show, and even a pageant. The first Summerfest was regarded as a success; the second event in 1969, was less successful, as it was plagued by additional venues, inclement weather, and severe financial debt. In 1970, a permanent central location was decided upon, and Summerfest moved to a former Nike missile site on the lakefront, where it continues to be held to this day. Also that year, Summerfest introduced its red "smiley face" logo, an insignia that has become synonymous with the event. The logo was designed by local graphic artist Noel Spangler.
It was also in 1970 that Henry Jordan became executive director of Summerfest, a title he held during the event's early years until his death in 1977. Another public face in that position was Elizabeth "Bo" Black,
, who became executive director in 1984. Through her fundraising and organizing, she became a local celebrity (and almost as much a recognizable part of Summerfest as the smiley face logo) until her ouster in September 2003. 
Summerfest celebrated its 40th edition in 2007. The event's history was the subject of "Summerfest Stories," a documentary that aired in June 2007 on Milwaukee Public Television.
The concerts have been mostly civil events, with two notable exceptions. In 1970, a performance by the late-arriving Sly & the Family Stone nearly resulted in a riot, and in 1973 a performance by Humble Pie & the Blackberries did result in a riot, along with a bonfire and about 300 arrests. As a result of the latter concert, organizers shied away from rock bands for several years, and established guidelines for "family-friendly" acts and a ban on alcohol brought in by patrons.
Live comedy acts have also been a part of Summerfest's history, even before a regular "Comedy Showcase" was first established in 1975. Bob Hope was the main headliner at Summerfest 1969, performing two shows at Milwaukee County Stadium. George Carlin (opening for Arlo Guthrie) performed his "Seven Words You Can't Say on Television" routine at the 1972 event (and was subsequently arrested for violating obscenity laws). Since 1975, comedy acts ranging from David Brenner and Henny Youngman to Jay Leno and Jon Stewart have performed at the event. Lewis Black has become a frequent performer at Summerfest, making near-annual performances since his first appearance in 1991.