Metal has so many subgenres and classifications it can be impossible to keep up with them all. It's so complicated at times that some bands don't even know what kind of music they play, and some self-described fans of certain subgenres have no idea what they're talking about. Not to mention all the bands who play versions of a certain subgenre but aren't considered "true" bands of that genre; looking at Deafheaven and black metal here.

With that in mind, it's a fool's errand to try to define any subset of metal with any sort of certainty. What do you do with all the bands that incorporate some parts of the genre and not all of them? What do you do with the bandwagoners and trendy bands who just want to get in on what's popular right now? What about crossover bands?

That being said, I'm going to try to elucidate here what's really going on right now. The biggest trend in metal these days is djent, a new-ish form of technical, progressive metal that's really captivating audiences and musicians alike. But what the hell is it anyway?

Let's get started. Djent as a term is an onomatopoeia that was coined by one of its first recognized practitioners -- Misha Mansoor of the band Periphery, also known by his online alias Bulb. It wasn't intended to describe a genre, but rather a guitar technique which, as it happened, came to define the genre. It was a way to describe the palm-muted riffs played by math-metal band Meshuggah. These kinds of riffs have come to be a vital part of the genre as a whole, and it could be said that Meshuggah was the first djent band completely by accident.

Since then, though, a wave of bands has taken up that mantle and run with it. Mansoor's band Periphery started to take off in 2008, and has gone on tour with major bands in the progressive-metal genre like Dream Theater. Other bands that ended up being lumped in with Periphery, whether they sounded all that similar or not, were Volumes, Tesseract, Textures, and Vildhjarta.

Some bands have been inducted retroactively because they were doing similar things already or they started doing them after the sound started to get really popular. These bands include After the Burial, Veil of Maya, Born of Osiris, and the Faceless.

How do so many bands, actively or retroactively, fit into the genre? Well, djent has, like emo, come to describe a number of different styles of metal that all share a few things in common. Number one, they're all pretty much progressive in some way. Whether that means featuring singing mixed in with screaming, keyboards and synths, or other tropes of progressive rock and metal, it now seems to fall in with djent fairly easily.

Since djent got popular, many bands have started adopting more and more progressive leanings too. After the Burial, for instance, employed a much more metalcore flavor before they ended up on the djent train. Then they started adding singing vocals and melodic, progressive passages to their songs.

Number two, most djent bands are highly technical. That means extreme adeptness with their instruments, long solos, and complicated riffs with complex time signatures, oftentimes played on seven- and eight-string guitars. That usually comes with progressive leanings, but not always. It is it's own trait, and it's something many bands have picked up on since djent started to explode.

Story continues on the next page.

That's also how bands like Animals as Leaders and Houston's own Scale the Summit, with their jazz-fusion leanings and completely instrumental music, can also sit comfortably under the umbrella of djent. They don't have some of the traits of djent, but they have the progressive and technical overtones to fit in.

Another common theme among these bands is that many of them are signed to the same record labels, especially Sumerian Records. As a whole, Sumerian isn't exclusively a djent label, but even bands who weren't formerly djent bands who have since signed with Sumerian have leaned towards it, probably due to pressure from the label. An example of that would be the latest Dillinger Escape Plan LP, One of Us is the Killer, which features a lot more of that sound on it than anything Dillinger ever released on another record label.

Now that you know what you're looking for with djent, though, why is it so damn popular? Well, who knows? It seems like whenever one band starts doing something interesting, every other band on the face of the planet wants to do the same. Then labels get involved and start shilling as much of it as they can to corner the market. Business 101, people.

Eventually this, like most metal subgenres, will get old to people and start to be rejected. Maybe metal will get simpler and more aggressive again. Maybe they'll cut out the singing and the complexity and do something more akin to the mid-'90s death metal of Cannibal Corpse. No one can predict the shifting tide of metal trends.

One thing is for sure though: djent is here to stay for now. It has swept over metal like a plague, and now every band and their grandma is going all in, so it's best to get acquainted. I, for one, welcome our new djent overlords.

ROCKS OFF'S GREATEST HITS

The Ask Willie D Archives Top 10 Bars, Clubs & Ice Houses On the Northside Top 10 Bars, Clubs & Ice Houses In the Galleria Area The 10 Lamest Bands of the '90s

• Metalocalypse