What's the formula for a hit record? Sure, lyrics provide the substance (there's no doubt about that), but it's impossible to deny the power of the right instrumental. This is the reason that talented rappers team up with hit-making producers in hopes of finding success. The right producer can bring out the very best in an artist and create magic in the studio.

So what happens when a producer makes a beat that's so powerful that all it needs is the right bars to make it massive? A few instrumentals that naturally come to mind are The Notorious B.I.G.'s "Who Shot Ya," co-produced by Diddy and Nashiem Myrick. The record is the beat of choice used by Funkmaster Flex for his infamous rants during his radio show on Hot 97. Then there's Jay Z's 1996 Ski-produced track "Dead Presidents." The beat has been used for countless rappers' freestyles from Lupe Fiasco to Drake to Lil Wayne, among others.

More contemporary examples, though, like Desiigner's "Panda," produced by U.K. producer Menace or Jahlil Beats' lauded "Hot Boy" record for Bobby Shmurda show that the original artist doesn't necessarily make the beat live up to its full potential, but rather it can sometimes be the other way around. This, in turn, brings the producers themselves to the forefront, becoming just as popular as the rapper who spit on the beat.

Hip-hop has a long history of genre-defining beats -- records that can take a rapper's lyrics to the next level. These beats produce undeniable game-changing (as well as life-changing) hits, define summers and stir up nostalgia no matter when their played. Here at XXL, we’re highlighting 20 classic hip-hop beats -- and of course there's many more in the game to choose from. Rappers, grab your pens and let the lyrics flow.