While the order in each decade is purely personal preference, there are several rules for a song qualifying for the list. First off, the band has to be notable. I'm not going to define what that means, but I'm sure you'd agree all the bands in the list are notable. There are plenty of riffs from obscure bands I'd rather put, but I know my love for Tarby doesn't make him the greatest riff maker of the 21st century. Second, each artist can only appear once in a decade, this is to prevent the best riff makers from hogging the list and adding some variety, showing how metal has changed over time. Decades are measured by when the song was recorded, not released, and when it's unclear the beginning of recording is used. This is mainly because a lot of definitive early metal songs were released in 1970, but recorded in 1969. Third, the song itself has to be notable. Here are things that can qualify as being notable: the song was release as a single, has music video made for it, was released as a single, was the title track for an album (note that Crawl through Knives meets this criteria because it was the original title for Come Clarity, and there is no way in hell Come Clarity is getting best riff of the decade ), is included on a greatest hits compilation album, was nominated for a Grammy or musical award of similar caliber, was included as a track in a notable film or video game, was covered by a notable band, or has a Wikipedia page for some miscellaneous reason. Finally, the song needs to be metal. Misirlou gets the pass despite predating metal as it was probably the single most influential song on the development of metal, and while many of the other songs in the other songs are better classified as hard rock, I can find a source listing them as heavy metal.

While this is my personal opinions, I invite you to challenge anything on my list, I pretty much just put the first thing that came to my mind that set the criteria I set for myself so I'm sure to have forgotten things and it's basically a first draft. The 2010s sections is particularly weak as most the bands I like from this decade are pretty obscure so I defaulted on overly popular bands, and it's still going on (so I'm purposely restricting it to just 8 songs for now as that's about how far we are through the decade). First thing to note is that is a list of best riffs, not best songs. It's not a list of best guitar work either, a riff is different from a solo or a fill (and yes, I had to make some calls between riffs and fills while making the list, tell me if I made any mistakes as sometimes it's hard to tell). Hopefully the riff I'm referring should be self-explanatory just by mentioning the song. Also note that this list under-represents styles of metal which deviate away from popular music, whether extreme metal, or "epic metal" (basically all post-Iron Maiden bands, power metal and melodeath), this is for two reasons: the first is because these bands tend to be less popular, so they would less recognizable and thus less likely to meet the notability requirement. Second, the style of these bands places less of an emphasis on melodic hooks, so a song tends to be less likely to have a signature riff. The reason Iron Maiden is not on the list is not because they don't have lots of great riffs, but rather because it's hard to pick a single riff which stands out above the rest (and don't say the Trooper, it's super overrated, Blitzkrieg Bop has a better main riff).

Now, onto the list...