November has arrived, which means 2016 will be a distant memory sooner than later. The holiday filled with spooks and candy may serve as the main event of the month, but October also marks the beginning of the fourth quarter in music, which is the last stretch of the year, where some of the biggest artists drop off new albums for the holiday season. The fourth quarter in rap was once a coveted period for an artist with an album set to be release, with all of the top heavyweights vying for Billboard chart supremacy and bragging rights.

However, the rap game has gone through many phases over the course of the past ten years, and the result has been an ever-changing landscape. Many major players that dominated the '90s and the early aughts began to fall to the wayside, while a new crop of new talent emerged, revitalizing the rap ecosystem. While rap music would suffer a bit, according to some fans, during this period of flux, the crop of new talent that had emerged, particularly in the south, would be hailed as the new kings of rap, among them T.I., Jeezy, Kanye West, Rick Ross, and Lil Wayne.

In 2016, the rap game looks to be going through another cycle of change, with the former upstarts turned kings beginning to make way for another crop of MCs to run things from 2016 until the foreseeable future. The fourth quarter has arrived again, and while mulling through the docket of upcoming releases, we couldn't help but have our minds drift down memory lane.

We've compiled the 20 most essential fourth quarter albums of the past decade to celebrate this time of year. Whether they established a new artist and helped mold their career, or were timeless bodies of work that stood out from the pack, here are 20 rap albums that defined the past decade.