[What Is Love?] is the fifth extended play (EP) by South Korean girl group Twice. The EP was released on April 9, 2018 by JYP Entertainment and is distributed by Iriver. It includes the lead single of the same name produced by Park Jin-young.
"What Is Love?" was written and composed by Park Jin-young, who previously produced "Signal", and it was arranged by Lee Min-woo "collapsedone", who co-produced "Knock Knock" and "Candy Pop". The song is about "the love girls would dream about or imagine after learning about it through books, movies or dramas" and was described as having a bright melody and uptempo dance beat incorporating trap.Twice members Jeongyeon, Chaeyoung, and Jihyo also took part in writing lyrics for two songs on the EP.