Album-oriented rock, abbreviated AOR, was originally an American FM radio format focusing on album tracks by rock music artists rather than singles releases.

The origins could well have been traced back to the classic Beatles 1967 album Sgt. Pepper's Lonely Hearts Club Band, an album that did not originally spawn any hit singles, so stations were forced to play only select tracks from the album, thus AOR was unofficially born.

In some markets the term AOR was re-positioned as Adult Oriented Rock, implying that 'adults' were more likely to buy albums rather than singles.

Some notable AOR bands:

• Boston
• Foreigner
• Journey
• Pink Floyd
• REO Speedwagon
• Survivor
• Toto

Album-oriented rock went through many stylistic changes on commercial radio in North America, including the United States, throughout the 1980's to add hair metal bands such as Warrant and Poison, expanding the classic rock playlist on such stations, and adding new-wave acts such as the Alarm and the Church until Nirvana's sudden ascent with the album Nevermind in 1991.

After the aforementioned album's success, album-oriented rock drifted into several current-based hard-sounding formats. One of these was active rock (euphemism for today's mainstream album rock, and playing acts such as Stone Temple Pilots, Guns 'N Roses, and Linkin Park). The active rock format was pioneered by the formerly broadcast (now internet only) KNAC-FM out of Long Beach, California in 1986 and expanded upon by WXTB-FM out of Tampa, Florida in January, 1990.

Another format spun off from AOR was Classic rock (mostly spanning the decades from the late 1960s to today, with more emphasis on the earlier hits).

Since then, hundreds of such rock stations have been playing both current-based active rock and the decades-spanning Classic rock to much commercial ratings success across the United States and Canada.

In the mid-to-late 1990s, AOR began to be associated with another concept called "melodic rock" which, most simply stated, is the sound of hard rock and heavy metal bands of the 70s, 80s, and early 90s. It is seen as a throwback to those eras and a counter-reaction against the grunge, alternative, bubblegum, retro-disco, and Latin sounds of the mid-to-late 90s. Many of these acts are bands, band members, and musicians from popular bands of the earlier eras, such as Toto, Foreigner, Van Halen, and Europe, either regrouped or playing in new bands or reconfigured lineups. Several of the acts are British or European, and many albums are now recorded and produced in Europe and Japan, and are only available in the U.S. as imports.