Y&T (originally known as Yesterday & Today) is an American hard rock/heavy metal band formed in 1974. They hail from the East Bay of the San Francisco Bay Area. The band released two studio albums on London Records as Yesterday & Today in the 1970s, before shortening their name to Y&T and releasing several albums on A&M Records beginning in 1981, as well as albums on Geffen Records, Avex Records, and others. The band was originally co-managed by Herbie Herbert (who also managed Journey) and Louis "Lou" Bramy. The band has sold over 4 million albums worldwide to date.

Yesterday and Today was formed in 1974 by Dave Meniketti (often mistakenly spelled Menketti), who started his musical career in 1973. The band's name was inspired by The Beatles' album of the same name. The original lineup consisted of Meniketti on lead vocals and lead guitar, Joey Alves on rhythm guitar, Phil Kennemore on bass, and Leonard Haze on drums.

The band released their first two studio albums, their self-titled debut and Struck Down, through London Records in 1976 and 1978 respectively. A new record deal in 1980 with A&M Records prompted the band to shorten their moniker to simply Y&T, and encores with fans chanting "Y&T, Y&T, Y&T" sealed the condensed name.

The band's first three studio albums under A&M, Earthshaker, released in 1981, Black Tiger, released in 1982, and Mean Streak, released in 1983, did not gain mainstream exposure, but are regarded as some of the band's best work. Songs off the record Earthshaker makeup an important part of the band's live shows.

Y&T's sixth studio album, In Rock We Trust, released in 1984, became the band's highest charting and selling album, reaching #46 on the Billboard 200. To date, it has sold over 450,000 copies, close to reaching gold certification status.

The band's 1985 hit "Summertime Girls", off their seventh studio album Down for the Count, became the band's highest charting hit to date, reaching #55 on the Billboard Hot 100 and #17 on the U.S. mainstream rock charts. It received tremendous airplay worldwide, played frequently in the Baywatch television series, is graced in several feature films, received heavy rotation on MTV as well as MTV’s top video playlists, and gets regular airplay today on classic rock radio stations throughout the United States.

Leonard Haze was replaced by Jimmy DeGrasso in 1986 and Joey Alves was replaced by Stef Burns in 1989. DeGrasso and Burns later played together with Alice Cooper in the 1990s.

Y&T's last studio album before their breakup was Ten, released in 1990. The album features some ballad highlights, such as "Don't Be Afraid of the Dark", "Ten Lovers", and "Come in from the Rain", together with a few straight-forward hard rock songs, including "Hard Times", "City", "Surrender", and the fastest track Y&T ever recorded, the speed metal song "Goin' Off the Deep End".

The band officially disbanded in 1991, concluding with the strong live album Yesterday & Today Live.

Y&T temporarily reformed in 1995 with a lineup of Dave Meniketti, Stef Burns, Phil Kennemore, and Jimmy DeGrasso, and performed sporadically afterward. The band officially reunited in 2001 with the same lineup, only with Leonard Haze replacing DeGrasso. Stef Burns left later on that year to join Huey Lewis and the News, and was replaced by rhythm guitarist/backing vocalist John Nymann, who was an old friend of the band, previously singing backing vocals on Down for the Count. In 2006, Haze was asked to step down and was replaced by Mike Vanderhule on drums. Dave Meniketti and Phil Kennemore have been the only constant members of the band since its formation in 1974.

In 2006, a complete concert in the Netherlands was captured on the live DVD One Hot Night. Y&T is currently in the studio recording a new album, which is due for release in late spring 2010. Once out, it will be their first proper studio album in thirteen years (since 1997's Endangered Species).