This feature was originally published on March 11, 2013.

When sorting out the greatest mixtapes of all time, you have to keep in mind what distinguishes a mixtape from an album: It's the most official that unofficial can get.

Mixtapes are rough around the edges. Often, they don't have the sheen of high-cost record company studio time. It's a mishmash of showcases: What's happened, what's to come, who someone holds as favored friends, as far as rappers and producers go. It's rapping over other people's beats. It's disses. It's gritty. It's fuck-ups kept on the track, skits that would never make it past a label, and samples that could never pass clearance.

That's what makes a great mixtape great. All of the spontaneous qualities that are too scruffy for a proper release, finally receive the proper treatment. And unlike a great album, the formula for a great mixtape isn't as refined, and it relies slightly more on the side of serendipity and luck, with the essential elements coming together the right way at that perfect moment in time.

These are the tapes that managed just that. From G-Unit and Lil Wayne to Dipset and Young Jeezy, allow us to re-introduce them: The 50 Best Rapper Mixtapes.

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