Base is the debut and only extended play by South Korean singer-songwriter Jonghyun, released on January 12, 2015 by SM Entertainment. Jonghyun collaborated with various artists for his album, such as Younha, Wheesung, Zion.T and Iron. His title song, featuring Iron as the rapper, is called "Crazy (Guilty Pleasure)" and was released digitally on domestic music sites on January 12, 2015, together with the album. On January 8, Jonghyun pre-released "Love Belt", another self-composed song which is a collaborative track with Younha, on MBC FM4U's broadcast of "Blue Night". The official music video for "Crazy (Guilty Pleasure)" was released on the same day, it features the rapper Iron who received attention with his performance on Mnet's survival show Show Me The Money 3. The concept of the music video takes after the name of the title song, guilty pleasure which means to enjoy something that you shouldn't. Jonghyun portrays a man who is head over heels for an alluring woman.Jonghyun started his official album promotions on KBS′ Music Bank on January 9. Jonghyun's music video to "Crazy (Guilty Pleasure)" was the most watched K-pop video in America and in the world for January 2015. As of 2015 the album has sold around 74,000 copies in South Korea. The album was reached US Billboard #1 World Albums, South Korea Goan #1 Weekly album chart.
The songs "Crazy (Guilty Pleasure)" (feat. Iron) and "할렐루야 (Hallelujah)" was co - written and produced by Dsign Music.