By the late 1960s "classic rock" period, a number of distinct rock music subgenres had emerged, including hybrids like blues rock, folk rock, country rock, southern rock, raga rock, and jazz-rock, many of which contributed to the development of psychedelic rock, which was influenced by the countercultural psychedelic and hippie scene. New genres that emerged included progressive rock, which extended the artistic elements; glam rock, which highlighted showmanship and visual style; and the diverse and enduring subgenre of heavy metal, which emphasized volume, power, and speed. In the second half of the 1970s, punk rock reacted by producing stripped-down, energetic social and political critiques. Punk was an influence in the 1980s on new wave, post-punk and eventually alternative rock. From the 1990s alternative rock began to dominate rock music and break into the mainstream in the form of grunge, Britpop, and indie rock. Further fusion subgenres have since emerged, including pop punk, electronic rock, rap rock, and rap metal, as well as conscious attempts to revisit rock's history, including the garage rock/post-punk and techno-pop revivals at the beginning of the 2000s.