Acid house is a pioneering genre of electronic dance music that emerged in Chicago during the mid-1980s, defined by the distinctive squelching, resonant sound of the Roland TB-303 bass synthesizer. Combining hypnotic basslines, repetitive rhythms, and stripped-back drum machine patterns, acid house became the soundtrack of the late-1980s rave movement, particularly in the UK where it fuelled the "Second Summer of Love." The genre is known for its energetic, psychedelic atmosphere, uplifting grooves, and emphasis on extended DJ mixing rather than traditional song structures. Influential artists and producers such as Phuture, DJ Pierre, A Guy Called Gerald, and Hardfloor helped shape its unmistakable sound, which continues to influence modern house, techno, trance, and countless other electronic music genres.