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Kendrick Lamar has released a surprise new album. It's called u**ntitled unmastered., and it's out right now on iTunes, Apple Music, Tidal, Spotify, and Google Play, via Aftermath/Interscope/Top Dawg Entertainment. It's the follow-up to last year's To Pimp a Butterfly. Details of the project first emerged tonight. Kendrick previously performed untitled tracks on "The Colbert Report" and "The Tonight Show Starring Jimmy Fallon." He also performed an unreleased verse at this year's Grammys ceremony. Revisit those performances below.

Update (3/4, 11:53 p.m.): The songs from Kendrick's "Colbert" and "Fallon" appearances both made untitled unmastered. They are now called "untitled 03 | 05.28.2013." and "untitled 08 | 09.06.2014.," respectively. (The latter was previously known as "Untitled 2.") Previously, part of Kendrick's "untitled 08" verse had been used for remixes of Funkadelic's "Ain't That Funkin Kinda Hard on You."

Update (3/4, 12:19 a.m.): Swizz Beatz has said on Instagram that his and Alicia Keys' 5-year-old son Egypt produced "untitled 07." TDE producer Sounwave has confirmed on Twitter that Egypt produced the second half of the track. Watch Egypt make the beat below, via Swizz's Instagram.

Update (3/4 9:08 a.m.): Adrian Younge and A Tribe Called Quest's Ali Shaheed Muhammad co-produced "untitled 06," a representative for Younge has confirmed. Cee-Lo Green also sings on the track. Younge and Muhammad are working on more music together.

Update (3/4, 12:52 p.m.): On Twitter, Kendrick clarified what untitled unmastered. is: "Demos from To Pimp A Butterfly. In Raw Form. Unfinished. Untitled. Unmastered."

Update (3/5, 11:16 a.m.): Responding to a fan inquiry on Twitter today, TDE label head Anthony Tiffith said a physical release of untitled unmastered. is in the works:

Read our Overtones column on Kendrick Lamar.

untitled unmastered__.__:

01 untitled 01 | 08.19.2014.

02 untitled 02 | 06.23.2014.

03 untitled 03 | 05.28.2013.

04 untitled 04 | 08.14.2014.

05 untitled 05 | 09.21.2014.

06 untitled 06 | 06.30.2014.

07 untitled 07 | 2014 - 2016

08 untitled 08 | 09.06.2014.

Watch Kendrick Lamar perform "Fuck Your Ethnicity" at Pitchfork Music Festival 2012: