2012–present: Debut, Mama

EXO-K and EXO-M's prologue single "What Is Love" was released on January 30, 2012, through iTunes and various online retailers from China and South Korea,^[10] where the single peaked at number eighty-eight on South Korea's Gaon Single Chart. On March 9, the group released their second prologue single "History,"^[11] which was written and produced by Thomas Troelsen and Remee. The single peaked at number sixty-eight on the Gaon Single Chart and number six on China's Sina Music Chart.^[12]
A concert showcase for the group was held in Seoul's Olympic Stadium on March 31, one hundred days after Exo debuted their first trailer on December 21, 2011.^[13] Approximately 3,000 fans from 8,000 applicants were selected to attend the showcase.^[14] A second showcase was held in the Great Hall of the University of International Business and Economics in Beijing, China on April 1.^[15]
EXO-K and EXO-M released their debut single "Mama" on April 8,^[16] followed by an EP, Mama, on April 9. On April 8, Exo-K made their debut performance on South Korea's music program The Music Trend, while Exo-M performed at China's 12th Yinyue Fengyun Bang Awards that same day.^[17][18] One day after release, "Mama" reached number one on various Chinese online retailers and music charts.^[19] Exo-M's album peaked at number two on China's Sina Album Chart, number five on South Korea's Gaon Album Chart, and debuted at number twelve on the Billboard World Albums Chart,^[20] while Exo-K's album peaked at number one on the Gaon Album Chart^[21] and debuted at number eight on the Billboard World Albums Chart.^[20] Exo-M's "Mama" music video peaked at number one on Chinese streaming websites, and Exo-K's version reached to number seven on YouTube's Global Chart.^[22]