So what exactly is a mixtape? A mixtape is a collection of music similar to an album, but it is not released with as much weight to it. Mixtapes are nearly always free and they are more used as a way to gain fans and notoriety than they are to generate sales. In other words, its goals are lower. Traditionally, a mixtape meant a project that was not released under a legitimate record label, and an album was any project released once an artist was signed. The definition gets muddy here as this is not to say that an independent artist cannot put out at an album. However much it defies definition, suffice to say: A mixtape is a more unassuming piece of music, and an artist’s mixtapes are often where one goes to find the beginnings of a legend’s career. Here are some of the greatest to come out in recent memory:

1. "1999," Joey Bada$$.

"1999" comes to us in the year 2012, but musically reflects 90s hip-hop sounds and aesthetics that make every old-school rap fan long for the “golden age” of hip-hop. Joey Bada$$, a high school student during the making of the project, marks the emergence of the generations raised on rap. What you hear on this project is someone who grew up listening to Tupac and Nas and Biggie, and someone who matches these musical roots with the raw talent to go toe-to-toe with any MC. Despite the fact that this sonic era preceded his very existence, Bada$$ paid it homage with a meandering fluid flow, and jazzy, hard snare-driven beats over bass lines as smooth as molasses. Any fans of old-school rap that feel perhaps the art form has lost its way take haven in the wordy raps and soulful beats of "1999."

2. "Acid Rap," Chance the Rapper.

Chance the Rapper seemingly came out of nowhere this year, an “internet rapper” who is being hailed as rap’s next superstar and performed at the Grammy’s while taking home a few himself. If you’re wondering what steps came along the way, look no further than the Chicago MC’s 2013 mixtape "Acid Rap." This piece of music displays a cohesiveness and thought not afforded to most mixtapes, as well as the creative vision of an artist bound to hit it big eventually. Chance portrays himself as a drugged-out teenager who still wants to promote a positive message. His energetic, spoken-word flow mixes flawlessly with the infectious instrumentals to bring us the foundations of an indie-rap star.

3. "So Far Gone," Drake.

People tend to forget: Drake was two mixtapes in at the beginning of 2009. Two mixtapes that had promise, sure: You could see Drake's ideas, where they were going, maybe even glimmers of potential. But it wasn't until "So Far Gone" that Drake's career kicked into hyperdrive. "So Far Gone" had a mix of classic young money swagger, summertime hits (“Best I Ever Had”), and the obligatory R&B tracks with the rapper guest spots, with Drake playing both parts. "So Far Gone" didn't just have hits, or great rapping, or great melodies, or deep cuts or stellar guest spots. It had coherence, narrative, and resonance that stands up even now. Let the debate over whether or not Drake has matched its greatness since carry on.

4. "Live.Love.A$AP," A$AP Rocky.

The first time we heard A$AP Rocky's "Purple Swag" and later "Pe$o," the most successful tracks off this mixtape, we knew he had something going for him. Many rappers search for years trying to find their voice and their sound, but what those songs suggested was that the Harlem rookie already had a fully defined aesthetic that was absolutely undeniable. When his mixtape finally dropped, our greatest hopes came true. Rocky draws inspiration from southern styles of rap without losing his NYC identity. Despite his laid-back persona, he came off as electric and precise on the microphone. The beats on the mixtape, mostly courtesy of Clams Casino and A$AP Ty Beats, bang so hard they bring Houston to Harlem. As Rocky says on "Purple Swag," "I'm Texas trill, Texas trill, but in NY we spit it slow." Whoever his influences are, "Live.Love.A$AP" marked the emergence of a new hip hop superstar.

5. "The Warm Up," J. Cole.

In the wake of Drake's "So Far Gone," there was a renewed interest in the mixtape scene for rappers who could mix wit, introspection, and candor. Enter: J. Cole. His second mixtape not only helped establish the young spitter, but the mixtape's track "Lights Please" famously impressed Jay-Z so much he signed Cole to Roc Nation. The mixtape helped Cole grow a buzz as he rapped over a series of classic beats like "Dead Presidents II" and "Last Call" and managed to do them justice. Yet it was on songs like "Grown Simba" and "Dollar and a Dream II" where Cole was able to establish his persona, setting him up as a relatable rapper with grand ambitions.