NSync's surprise album was released by Sony Legacy Records last July 29, said a report from Billboard. The release of the greatest hits album "The Essential NSync," which comes 12 years after the group split, was so top secret that even the members of the 90s American boyband did not know about it.

Singer Lance Bass took to Twitter his surprise over the release of the NSync surprise album, sarcastically tweeting: "I love when the record label doesn't even tell you they are releasing a new 'NSYNC album tomorrow ! #TheyCare".

Bass' tweet also had an Amazon link to the said NSync surprise album. The two-disc recording was available on Amazon early July 29, but quickly sold out after news of the surprise release started circulating.

According to the Billboard report, the unannounced release of the NSync surprise album probably generated more publicity, and as a result sold out whatever small quantity it had.

The quick consumption of the "The Essential NSync" was also probably due to fans thinking that the greatest hits compilation would be the closest they would get to a much-anticipated NSync reunion album, said Billboard.

A report from ryanseacrest.com reviewed the album, which contains fan favorites from the hit group, such as "I Want You Back," "Tearin' Up My Heart," "Bye Bye Bye," and "It's Gonna Be Me".

Songs in "The Essential N Sync" include sentimental tracks such as "God Must've Spent A Little More Time On You", "Thinking Of You (I Drive Myself Crazy)", "This I Promise You", "I Believe In You", "Gone", "Sailing", "Somewhere, Someday", "If Only in Heaven's Eyes", "Selfish."

N Sync's upbeat hits are also part of the album, with songs such as "Pop", "The Lion Sleeps Tonight", and the Neptunes remix of "Girlfriend".

Other tracks include: "More Than a Feeling", "Best of My Life", "You Don't Have to Be Alone", "On the Line", "That Girl (Will Never Be Mine)", "Falling", "Feel the Love", "See Right Through You", and "Believe in Yourself."