It's hard to pin down the defining sound of a decade only a few years later. Those growing up in the 90s wouldn't have seen grunge and Britpop as the complete relics we do today, instead viewing them as an organic part of a far more varied musical landscape. Similarly, although the 2000s will eventually be looked back upon as a condensed version of itself, it's impossible to pick out such everlasting features right now. However, a broad look back over ten years can unearth some likely candidates. There's no denying that the first decade of the 21st century will be seen as a crucial one in the history of popular music. A number of albums we now regard as modern classics were introduced to the world between 2000 and 2009, from a wide variety of genres. From revolutionary rap LPs that changed to face of hip hop production, to zeitgeist-altering indie rock masterpieces, the decade provided innovation and freshness in abundance. Here are 50 albums which best defined the 2000s, from mainstream superstars such as Kanye West and Green Day to critically acclaimed darlings Radiohead and Arcade Fire. Some treasured favourites will certainly be left out - so be sure to leave your own suggestions in the comments section below.