>>1
First there was the Chicago house sound of dance music ("dance music" is what people called it instead of calling it disco in the mid to late 1980s). 1970s disco started out as a dance funk with ordinary instruments and a horn section to boot, but then disco evolved with overt electronic rhythm and effects, as in Donna Summer - I Feel Love produced by Georgio Moroder. Chicago House would carry over electronic elements but only as the general 1980s trend in all music concurrent with Eurodisco/Italiadisco, and there'd be soul-style vocals still pretty typically. Detroit techno took that and had more overtly electronic factory-sounding rhythms, and England hopped on with the whole acid house rave thing. Some styles were sample-heavy, others were just spare electronic rhythms which might repeat very much or slowly evolve or mimic the chanting savages high on cactus drugs, which is pretty much what trance or chillout music can be. Techno as an umbrella term spawned ten thousand subgenres (it seems, as people keep trying to come up with more god damn genre names) drum 'n' bass, gabber, big beat, hardcore, ... etc., dubstep (which itself has elements of the dub style of reggae combined with the sound effect in Mr. Oizo's Analogue Worms Attack mutated countless ways).