Progressive rock (often shortened to "progressive", "prog rock" or "prog", also sometimes called, although not synonymous with, "art rock") is a form of rock music that evolved in the late 1960s and early 1970s as part of a "mostly British attempt to elevate rock music to new levels of artistic credibility".

Progressive rock bands pushed "rock's technical and compositional boundaries" by going beyond the standard rock or popular verse-chorus based song structures. Additionally, the arrangements often incorporate elements drawn from classical, jazz, and avant-garde music. Instrumental songs are more common, and songs with lyrics are sometimes conceptual, abstract, or based in fantasy. Progressive rock bands sometimes used "concept albums that made unified statements, usually telling an epic story or tackling a grand overarching theme".

Progressive rock developed from late-1960s psychedelic rock and jazz fusion, as part of a wide-ranging tendency in rock music of this era to draw inspiration from ever more diverse influences. The term came into most widespread use around the mid-1970s. While progressive rock reached the peak of its popularity in the 1970s and early 1980s, neo-progressive bands have continued playing for faithful audiences in the subsequent decades. Progressive rock sharply declined in popularity for much of the 1980s, but returned to prominence in the early-to-mid 1990s.

Subgenres and related genres as categorised by the popular progressive rock site Prog Archives include Canterbury scene, crossover prog, experimental metal/post-metal, heavy prog, Indo-prog/raga rock, jazz rock/fusion, Krautrock, neo-prog, post-rock/math rock, progressive electronic, progressive folk, progressive metal, psychedelic rock/space rock, RIO/rock in opposition/avant-prog, rock progressivo italiano, symphonic prog, tech/extreme prog metal, and zeuhl. Symphonic prog is probably the sound most commonly associated with the genre, as most of its most influential acts at least dabbled in the style, and many of its most acclaimed albums (especially Close to the Edge by Yes, Selling England by the Pound) are exemplars of the style.

Though frequently lambasted by critics, the genre continues to have a lasting influence on modern music, perhaps because its demonstrations of musical and compositional skill hold particular appeal to musicians, who have added appreciations for how difficult these styles are to perform. In addition to genres like post-rock, math rock, Krautrock, and experimental metal, already mentioned above, the genre is also an unmistakable influence on video game soundtracks. Perhaps because prog acts were early pioneers in incorporating synthesizers into popular music, some of the most influential video game composers in the world, including 近藤浩治 (Kōji Kondō, best known for his work on the Super Mario Bros. and The Legend of Zelda) series) and 植松伸夫 (Nobuo Uematsu, best known for his work on the Final Fantasy series), have explicitly cited prog acts like Emerson, Lake & Palmer, Pink Floyd, and Deep Purple as some of their most important influences; 菊田裕樹 (Hiroki Kikuta, best known in the West for Secret of Mana), another VGM composer influenced by prog, also suggested that their shared love of bands like Emerson, Lake & Palmer may have been the tipping point that pushed Uematsu to hire him to compose for Square.

In a perhaps more unexpected case, some critics have also argued that prog has influenced the works of many alternative hip-hop acts such as Atmosphere, Aesop Rock, Cage, Caparezza, dälek, Kid Cudi, Lupe Fiasco, and Kanye West, many of whom have also sampled prog acts (most famously, West sampled "21st Century Schizoid Man" for "Power").