A remix (or reorchestration) is a piece of media which has been altered or contorted from its original state by adding, removing, and/or changing pieces of the item. A song, piece of artwork, book, video, poem, or photograph can all be remixes. The only characteristic of a remix is that it appropriates and changes other materials to create something new.

Most commonly, remixes are a subset of audio mixing in music and song recordings. Songs may be remixed for a variety of reasons:

to adapt or revise a song for radio or nightclub play

to create a stereo or surround sound version of a song where none was previously available

to improve the fidelity of an older song for which the original master has been lost or degraded

to alter a song to suit a specific music genre or radio format

to use some of the original song's materials in a new context, allowing the original song to reach a different audience

to alter a song for artistic purposes

to provide additional versions of a song for use as bonus tracks or for a B-side, for example, in times when a CD single might carry a total of 4 tracks

to create a connection between a smaller artist and a more successful one, as was the case with Fatboy Slim's remix of "Brimful of Asha" by Cornershop

to improve the first or demo mix of the song, generally to ensure a professional product.

to improve a song from its original stateRemixes should not be confused with edits, which usually involve shortening a final stereo master for marketing or broadcasting purposes. Another distinction should be made between a remix, which recombines audio pieces from a recording to create an altered version of a song, and a cover: a re-recording of someone else's song.

While audio mixing is one of the most popular and recognized forms of remixing, this is not the only media form which is remixed in numerous examples. Literature, film, technology, and social systems can all be argued as a form of remix.