Start here
You do not need to know any of the words yet. Answer four questions about what you want to hear: how the singing goes, how heavy, how fast, and roughly when, with one or two more if that leaves a tie. This ranks all 150 genres in the encyclopedia against your answers, then hands one of them back with five records in an order.
Every question is matched against something the encyclopedia already stores, and the result shows its own arithmetic. Nothing is remembered anywhere but in this page's address, which is also how you send it to somebody.
Question 1 of at most 6
When someone is singing, what should come out?
This is the axis that decides whether a newcomer finishes a record. Everything else on this page is a matter of degree; this is a matter of kind, which is why it counts for three times an era answer.
Hear the difference
Two records at almost the same weight of guitar. The only thing that differs is the throat.
- The voice doom never gave up
Candlemass - Epicus Doomicus Metallicus
A full, high, operatic clean vocal over the heaviest thing on the record. Every other extreme genre in this tree eventually abandoned singing; doom decided the weight came from the guitars and left the melody alone.
Open on YouTube - The growl, doing a drummer's job
Follow the vocal against the riff rather than against the melody, because there is no melody to follow it against. It lands with the accents, and where a singer would hold a note it simply stops.
Open on YouTube
Both are sound passages from the genre pages, cued to the second. Nothing reaches Google until you press play.
Or, if you already know a name
The 28 genres sitting one step below the two roots, which is the tree's own answer to which are the broad ones rather than a shortlist of what somebody decided is famous. Anything deeper works too: search for it, then follow "New to this?" from its page.