Base is the debut and only extended play (EP) by South Korean singer-songwriter Jonghyun, released on January 12, 2015 by SM Entertainment.

The EP was commercially successful, debuting at number one on South Korea's Gaon Album Chart.

[2] The same rhyme scheme was later adopted by the remaining Shinee members; Key named his solo debut album Face (2018), followed by Onew with Voice (2018) and Minho with Chase (2022).

[3] Describing the EP, Jonghyun told the media at a showcase: To be honest, I am not confident in singing ballad songs.

[4]Jonghyun wrote lyrics for all the songs on the EP,[4] and composed five of them himself: "Déjà-Boo", "Love Belt", "Neon", "Beautiful Tonight" and "Fortune Cookie".

Iron was featured on "Crazy (Guilty Pleasure)" at his company's suggestion after he elected to include rap in the song.

[2] Jonghyun wanted a female vocalist for "Love Belt", and opted for Younha after listening to the Epik High song "We Fight Ourselves", on which she features.

[2] "Beautiful Tonight" was composed as early as 2012 and was inspired by the view of the moon as Jonghyun was walking home from work one night.

[10] "Crazy (Guilty Pleasure)" is a midtempo retro pop song containing neo soul and funk influences.

[19] Finally, "Fortune Cookie", which is exclusive to the CD version, is a neo soul song with a broken beat.

[7] On January 8, Jonghyun played "Love Belt" on his MBC radio show Blue Night.

[11] The concept of the music video reflects the name of the song, "guilty pleasure", and depicts Jonghyun as a man who is "head over heels for an alluring woman".