Over the better part of the last four decades, an innumerable amount of rap albums have been released. During the genre's humble beginnings, most of these albums were products of rappers from the East Coast -- New York, in particular. But throughout the '80s, the locales changed and became more widespread, with MCs as fas as the West Coast dropping projects. The '90s saw the continued expansion of hip-hop with the South and the Midwest getting in on the fun and introducing the world to their unique sounds.

Before long, there was a melting-pot of artists with varying styles all contributing to the growth of the culture. By 2000, 20 years had passed since the first official rap LP had become an actual thing. There were certain albums that deserved praise and required listening for any rap aficionado. Familiar names of albums that fall in this elite class include N.W.A's Straight Outta Compton, Nas' Illmatic and OutKast's Aquemini.

As hip-hop became more popular, more albums arrived. Soon, many great works by deserving artists were heralded by critics, but largely ignored by the average rap fan. Perhaps there was just too much music to consume at the time or the albums promoted on MTV and BET video countdowns were favored rather than the under-marketed major label MC or indie stalwart. That's why we decided to highlight albums that rarely get the just due they deserve. Some are from artists you may be familiar with while others you may not have heard a day in your life. Either way, these selections from their respective eras are solid.

This is not a definitive list of the most underrated projects by any means, but rather the standout albums from different eras you need to hear. Check out 20 Underrated Rap Albums You Need in Your Collection.