A "school", or aesthetic, of electronic music composition and performance that arose in the San Francisco, California area in the 1960s. The style first arose around 1960 as a fusion of the styles of the modern-classical composers working in the area, and technologists experimenting with electronic sound creation. At the time, no packaged music synthesizers existed (other than a few large installations, such as the RCA Synthesizer, which were all in the New York City area). So these composers turned to tape techniques, establishing the San Francisco Tape Music Center in 1962.
However, Don Buchla's work on voltage-controlled synthesizers starting in 1964 quickly became a significant influence. Buchla's early instruments both reflected and encouraged the avant-garde techniques of the San Francisco performers. Buchla's synths did not have conventional keyboards; they mostly used rows of touch pads and alternative controllers such as joysticks. The method of synthesis also relied more on VCOs capable of producing complex timbres through generation of unconventional waveforms and wave shaping. The West Coast aesthetic encouraged improvisation with parameter tweaking during performance, and the use of alternate scales and tunings, which the Buchla synths were designed to support. There was also a DIY component; performers were encouraged to modify their instruments and design their own circuits. A lot of equipment from the tape-studio era remained in the hands of performers, so things like function generators and edited tape loops were often incorporated with the synths.
Today, there are still groups of performers that continue to maintain the West Coast school, although most of the action centers around Los Angeles rather than San Francisco now. The preferred method of synthesis still revolves mostly around complex-timbre oscillators and frequency modulation techniques, although a significant additional element has been added in the form of complex sequencing, borrowed from the Berlin school. The West Coast also tends to prefer synths that are physically smaller and have a higher density of circuitry to packaging; panels are often small and rather cramped. In terms of music style, avant garde and improvisation is still a major influence.