Square Up is the first Korean extended play (second overall) by South Korean girl group Blackpink, released on June 15, 2018 by YG Entertainment. It is available in two versions and contains four tracks, with Ddu-Du Ddu-Du released as the lead single. Ddu-Du Ddu-Du peaked at number one in South Korea for three weeks and became the highest-charting song by a female K-pop act in the United States and United Kingdom. The song Forever Young was later promoted in Korean music programs and peaked at number two in South Korea.
Upon its release, Square Up debuted atop the Gaon Album Chart and went on to sell almost 179,000 copies on its first fifteen days of release in South Korea. The EP also debuted at number 40 on the US Billboard 200, becoming Blackpinks highest selling album in a Western market as well as the highest-charting album by a female K-pop group at the time. In March 2019, it was certified Platinum by the Korea Music Content Association (KMCA) for selling 250,000 units.