Girls' Generation (Hangul: 소녀시대; So Nyeo Si Dae), also known as SNSD, is a South Korean girl group formed by S.M. Entertainment. The group is composed of eight (formerly nine) members: Taeyeon, Sunny, Tiffany, Hyoyeon, Yuri, Sooyoung, Yoona, and Seohyun. Girls' Generation officially debuted on August 5, 2007 with its debut single "Into the New World" and subsequently gained some attention with their self-titled debut album. However, it was not until 2009 that they rose to prominence with the single "Gee", which claimed the top spot on KBS's Music Bank for a record-breaking nine consecutive weeks and was named the most popular song of the 2000s decade by Melon. The group solidified their place in the South Korean music industry with follow-up singles "Tell Me Your Wish (Genie)", "Oh!", and "Run Devil Run" from late 2009 to early 2010.
In mid-2010, the group signed with Nayutawave Records (present-day EMI Records Japan) to embark into the Japanese music scene. In April 2011, Girls' Generation's Japanese self-titled debut album was released, which peaked atop the Japanese Oricon Albums Chart and became the first album by a South Korean girl group to achieve a double Platinum certification by the RIAJ. The group returned to the South Korean music scene in October 2011 with The Boys, which has sold over 457,000 copies in South Korea, becoming the best-selling album in the Gaon chart history since its launch in 2010. During this time, the group also expanded their endeavor to the United States by signing with Interscope Records. In 2013, Girls' Generation's fourth Korean studio album titled I Got a Boy was released. The title track was subjected to major attention from western media after it was awarded Video of the Year at the inaugural YouTube Music Awards.
Girls' Generation has sold over 4.4 million albums and 30 million digital singles as of 2012. The group's immense popularity in its native South Korea has earned them numerous accolades, notably titles such as "The Nation's Singers" and "The Nation's Girl Group". Girls' Generation is also regarded as the most popular K-pop girl group in Japan alongside Kara; the group is the first South Korean girl group to have two number-one albums on the Japanese Oricon Albums Chart. Korean newspaper Asia Today placed the group at 45 on its 50 Korean Power Leaders list in 2011.