Girls' Generation (Korean: 소녀시대; RR: Sonyeo Sidae), also known as SNSD, is a South Korean girl group formed by SM Entertainment. The group is composed of eight members: Taeyeon, Sunny, Tiffany, Hyoyeon, Yuri, Sooyoung, Yoona, and Seohyun. Originally a nine-piece ensemble, member Jessica departed from the group in September 2014. Among the most known South Korean figures and successful K-pop groups worldwide, Girls' Generation has earned numerous accolades and the honorific nickname "The Nation's Girl Group" in their home country.

Girls' Generation debuted on August 5, 2007, with the single "Into the New World" from their eponymous Korean album. The group rose to fame in 2009 with the single "Gee", which claimed the top spot on KBS's Music Bank for a record-breaking nine consecutive weeks and was Melon's most popular song of the 2000s decade. The group cemented their popularity in Asia with follow-up singles "Genie", "Oh!", and "Run Devil Run", which were released between mid-2009 and early 2010. Their second Korean studio album, Oh! (2010), won the Golden Disc award for Album of the Year (Disk Daesang), making the group the first and only female act to win the Album Daesang.

Girls' Generation ventured into the Japanese music scene in 2011 with their eponymous Japanese album, which became the first album by a non-Japanese girl group to be certified million by the RIAJ. The group's third Korean studio album, The Boys, was the best-selling album of 2011 in South Korea. An English version of the single "The Boys" was released in an attempt to expand the group's endeavor to the global music scene. The group's fourth Korean studio album, I Got a Boy (2013), was supported by the title track, which won Video of the Year at the inaugural YouTube Music Awards. Girls' Generation continued to build upon their popularity with their fifth and sixth Korean studio albums, Lion Heart (2015) and Holiday Night (2017). Following a five-year hiatus to focus on their individual careers, they returned with their seventh Korean studio album Forever 1 (2022).

The group's signature musical styles are characterized as electropop and bubblegum pop, though their sound has varied widely, incorporating various genres including hip hop, R&B, and EDM. In 2017, Billboard honoured Girls' Generation as the "Top K-pop Girl Group of the Past Decade". They are the first Asian girl group to achieve five music videos with over 100 million views on YouTube with "Gee", "I Got a Boy", "The Boys", "Mr. Taxi", and "Oh!". In Japan, they became the first non-Japanese girl group to have three number-one albums on the Oricon Albums Chart, and their three Japanese concert tours attracted a record-breaking 550,000 spectators.