A little bit more detail on trance:
Trance isn't really a very cohesive genre, and several scenes that now describe themselves as trance genres actually developed more or less independently of each other. The common stylistic origin that I would say they have is the minimalist works of Tangerine Dream and Jean Michelle Jarre. The slow, fluid, hypnotic aspects were fundamental to the shifts in three major scenes: German Rave, British Acid House, and Electronic Body Music.
Sven Väth brought these concepts into the German Rave scene, and from his experimentations emerged German Trance, which was basically Tech Trance before it became necessary to append the "tech" moniker.
Meanwhile, progressive minimalism was being introduced to the Acid House movement by The KLF, and a few other artists, yielding Acid Trance.
And at the same time, hippies in Goa, India were infusing Electronic Body Music sounds with the hypnotic sounds of Ambient and the trippy sound effects of Psychedelic Rock (as well as their affected Hindu mysticism), yielding Goa Trance.
From here, things got really complicated:
At some point, Prog House picked up elements of all three genres, making Prog Trance, which called itself trance, and retroactively applied the name to the other three genres, necessitating German Trance calling itself Tech Trance. Goa picked up more and more Tech Trance elements, yielding Psytrance (at some point, they also sampled a bunch of Metal music, making Heavy Metal Goa). (Also note that a lot of the original hippies behind Goa don't prefer to lump Goa in with Psytrance, but they're the minority, and most Psytrance listeners, producers and DJs put the two in the same genre anyway.) Acid Trance plugged along on its own for a while. Balearic Beat also started mixing in Trance concepts, which made Ibiza Trance.
This is about the same time Sasha made Trance Hot Shit(tm) and everyone and their mother started making the stuff. It was in this period that Hard Trance, Melodic Trance, and Vocal Trance showed up, taking elements from prog trance and Ibiza trance and kinda driving them into the ground. At this point, Acid Trance promptly fizzled out like the flash in the pan it was.
Meanwhile, Goa had been replaced entirely with the Psytrance scene, and proceeded entirely independent of the rest of the trance scene. I'd say that from this point, five subgenres calcified: Suomisaundi, Full-On Psytrance, Minimal/Progressive Psytrance, Melodic Psytrance/Morning Trance, and Dark Psy.
All in all, I'd say Trance's lineage looks roughly like this. Unless otherwise noted, influence flows from left to right:

Note that although Ishkur really intended "Dutch" Trance as a joke in order to take the piss out on DJ Tiësto, Ferry Corsten, and Armin van Buuren (who incidentally made three different kinds of trance), the term actually can be useful in describing the common element of protracted breakdowns.