"Bang!" is the third single released by South Korean girl group, After School. The single marked the first appearance of the group's eighth member, Lizzy. It was later released in Japanese for the group's Japan debut. The single was released on 17 August 2011 in 3 editions. This version doesn't include ex-member Bekah, who left the group after the end of promotions for the group's first Korean album "Virgin" to become a designer.

"Bang!" is After School's third Korean single. The title track, which was used as the lead single, was originally planned to be included in After School's second single "Because of You", but was delayed due to the lyricist and composer wanting to make the track more complete. The single's concept displayed the group wearing sexy marching band outfits, and it was later revealed that Kahi was the mastermind behind the concept. Kahi stated after watching the American film Drumline, she fell in love with the marching band style and wanted to do a marching band concept ever since she took to the stage as an After School member. The group practiced playing the drums for five months with a trainer for the concept. It was the first release to feature third generation After School member Lizzy.

The title track reached #17 on the Gaon 2010 digital download charts with 2,374,731 copies sold.

More than one year later, the single was released as their official Japanese debut under the stage name After School. The single was released in three versions, two CD+DVD editions and one CD Only edition. Both CD+DVD editions include the same track list, however A edition features contents in Japanese, while B edition does it in Korean. CD only edition also includes the original Korean version of the song, plus two instrumental tracks.

After School was accused of choreographic plagiarism after German dancer and choreographer Camillo Lauricella received messages saying that the group "...stole some of our moves for their music video of their song "Bang!"". Lauricella further stated "On the one hand its cool & flattering. But on the other hand... What do you guys think?" Lauricella and his good friend Nika Kljun originally created the choreography to Black McGrath's song "The Night" and uploaded it on YouTube in February 2010.

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