Final answer:
Grunge is the genre that originated in the 1980s in the Pacific Northwest, specifically Seattle, and became widely popular in the 1990s as a type of alternative rock. It featured heavier music, introspective lyrics, and a rejection of the glam look.
Step-by-step explanation:
The genre that originated in the 1980s as a regional style and became the best-known type of alternative rock in the '90s is grunge. This style emerged from the Seattle music scene and differed significantly from other rock genres of the time. Bands in the grunge movement, which played hard rock with a distinct punk-rock aesthetic, often detuned their guitars for a heavier sound and offered lyrics that took political stances or dealt with heavier themes such as mental illness, and the dark side of drug dependency, contrasting the party-centric lyrics common in mainstream rock. Seattle's grunge scene, wearing unremarkable clothing like flannel shirts, stood in opposition to the spandex-and-makeup aesthetic of 'hair metal' bands.
Grunge bands were initially playing for local audiences in the Pacific Northwest, creating what could be called a type of folk music unique to the area. By the early 1990s, however, these bands achieved international fame and grunge became a significant cultural force. The style's impact is evident in bands like Nirvana, Pearl Jam, and Soundgarden, who gained global recognition and defined the sound of the era.