In hip-hop, more than any other genre, a musical collaboration has the ability to transcend, to become an event. Or, even better, a competition.

The spirit of trading bars regularly drags the best out of an already-cocky lot, and a well-executed feature can not only make a hit (club, street, radio or otherwise) but a career. Just consider the role “Live at the Barbecue” played in the career of Nas, how Lord Finesse’s “Yes, You May (Remix)” introduced us to Big L, or all the heads Canibus turned by snatching the mic off LL Cool J’s arm on “4, 3, 2, 1.”

An invite to cameo should be considered a proposition, a dare—to swing by the studio and steal the song out from under the headliner. For some cameo artists, it’s a chance to puff their chest. For others, it’s an opportunity to experiment in a fresh context, to see how their styles and words work in a world other than their own.

So while the 1990s certainly ushered in the popularity of the featured artist—how many Dr. Dre songs were just excuses for a young Snoop Dogg to shine?—the 2000s have proudly carried the tradition forward.

Some of the following 35 guest verses introduced us to future stars, incited dis wars or pumped up the track to smash-hit status. But they all gave us shivers and compelled us to reach for the rewind button. —Luke Fox

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