Modern rock, also known as alternative radio, is a genre encompassing rock music prevalent on college rock radio stations, notably used to distinguish itself from classic rock originating in the 1960s–1980s. The format, largely based on alternative rock, is frequently featured on commercial radio and emerged from hardcore punk, notably referring to alternative rock music since the 1980s.

Several modern rock radio stations existed in the 1980s. 1988 marked the formal establishment of modern rock as a radio format with Billboard's creation of the Modern Rock Tracks chart. This chart relied on inputs from college and commercial stations. The format gained prominence after grunge bands like Nirvana and Pearl Jam's success in 1991, prompting many American stations to switch to this format. Some consider modern rock a specific subset of alternative rock.

The format's evolution can be divided into classic modern rock and the contemporary alternative rock format. Pre-grunge, the format embraced danceable music from various artists with ties to new wave and the Second British Invasion. Initially, few American artists ranked on the modern rock chart. Between 1992 and 1994, female, foreign, and dance music diminished, leaving mostly American male-created guitar rock. By 1996, the modern rock chart mirrored mainstream rock, surveying prevalent rock music.

During the 2000s, modern rock stations predominantly featured songs from the active rock format, notably post-grunge and nu metal, stemming from the 1990s grunge and alternative metal movements. Early 2000s modern rock included diverse artists like Jack Johnson, Muse, Coheed and Cambria, The Postal Service, The Mars Volta, Junior Senior, Snow Patrol, Story of the Year, The Black Keys, and Kings of Leon. Mid-2000s witnessed post-punk, garage rock, noise rock, and dance-punk revival alongside enduring post-grunge and nu metal success.

Presently, modern rock revolves around an indie-driven radio format spotlighting emerging and recent indie rock bands. A wide range of genres like reggae, folk, hip hop, and EDM is incorporated, with prominent indie rock artists such as Young the Giant, Of Monsters and Men, Atlas Genius, The Neighbourhood, Arcade Fire, Weezer, Twenty One Pilots, The 1975, Arctic Monkeys, and Bastille. As of February 2014, indie rock remains a staple on modern rock radio.