Hard Rock and Heavy Metal

My general definition for metal is such as this:

1. There needs to be at least one distorted instrument (generally stringed instrument, this can be anything from an electric guitar to a synth patch to a distorted cello)
2. It has to be based on riffs. This separates it from punk, which is more based on fast drums and several bars of abrasive chords.
3. It is not based on elements found in pop music such as catchyness or ability to sing along. It can have pop elements, just not a ton.

This generally works for me, even though I'm more of a know-it-when-I-hear-it person.

The definition isn't perfect though. For example, Within Temptation's "The Heart of Everything" and "Addicted" by Devin Townsend wouldn't qualify by rule 3.

My first rule of thumb is simply a general "Does it sound more like metal or rock?" - that's a good place to start, and it's usually guitar tone that gives the game away, or riff styling - rock will tend towards 12-bar, with a kind of "swagger" or swing. Metal tends to avoid swing, going for sharper, more angular riffs.

harmonium.ro wrote: "Concrete music" is already taken

Point well taken. Though it doesn't use riffs

^I don't think I'll ever make a definition that even I can agree with. And if I could it wouldn't align with this website, because there are a lot of bands that this site accepts that I would outright reject.