Final answer:
Grunge rock is a music genre developed in Seattle in the 1980s, characterized by distorted guitars, heavy sound, serious lyrics, and a non-glamorous fashion style. It moved from local fame to international popularity in the early 1990s with bands like Nirvana and Pearl Jam.
Step-by-step explanation:
Grunge rock is a subgenre of alternative rock that emerged in the mid-1980s in the Pacific Northwest, particularly in Seattle, Washington. It is characterized by a fusion of punk rock's edge and heavy metal's sound, often featuring distorted electric guitars, contrasting song dynamics, and raw, angst-filled lyrics. Grunge bands like Nirvana, Pearl Jam, Soundgarden, and Alice in Chains were distinct in their appearance and musical style, preferring to wear plain clothing like flannel shirts over the flashy attire of their contemporaries.