A radio edit is often just a slightly different arrangement that makes a song conform to a more traditional pop structure, with a duration of 3 to 4 minutes. Some radio edits are just "early fades," being shorter only by virtue of not being allowed to play to completion. Since it is usually shorter than the original version, a radio edit is more cost-effective for commercial radio stations, allowing more time for commercials and other content to be programmed. Radio edits are often released as singles. An example of a song that is simply shorter than the LP version is Depeche Mode's "Enjoy the Silence".
On rare occasions, however, very long songs do not have a radio edit, despite sometimes being six or seven minutes in length. The most famous example of this would be "Bohemian Rhapsody" by Queen, which is just under six minutes in length but never radio edited (despite still receiving reasonable radio airplay today).
Radio edits are also created to conform to decency standards imposed by government agencies, such as the Federal Communications Commission in the United States. As some popular songs would violate these standards in their original consumer form, music publishers often provide radio stations with censored versions intended for broadcast. In such edits, vulgar or very explicit lyrics are replaced with either silence, sound effects or a constant "bleep" tone, which is usually 1 kHz. Since the editing is often performed by studio mixing engineers, usually only the vocal track is affected.
In cases where the song's subject matter may also be deemed inappropriate, an entirely new version of the song may be recorded for radio. An example of this is D12 and Eminem's "Purple Pills", which was recorded as Purple Hills featuring greatly altered lyrics which removed many references to drugs and sex.
Some songs also are also released to radio stations with more than one radio edit. Examples of this include Eminem's "Ass Like That", which had a radio edit censoring "Ass" and a more lenient one leaving it intact, and Vanilla Ninja's "Cool Vibes", which had a 04:38 radio edit and a shorter, three-minute version for use in the build-up to the Eurovision Song Contest 2005.
Radio edits which shorten the song but do not censor 'bad language' are sometimes referred to as "dirty edits".