A signature song is the one song (or, in some cases, one of a few songs) that a popular and well-established recording artist or band is most closely identified with or best known for, even if they have had success with a variety of other songs. There have also been instances where a film actor has acquired a signature song by giving a popular vocal performance in a feature. Signature songs can be the result of spontaneous public identification, or a marketing tool developed by the music industry to promote artists, sell their recordings, and develop a fan base.