A musical intro is the beginning of a piece of music, and can take many forms. A PRELUDE is a short piece of music that introduces a larger work, often with a slower tempo and more subdued mood. An OVERTURE is a longer piece of music that typically has a faster tempo and more upbeat mood. A prel is a short piece of music that is similar to a PRELUDE, but is usually more improvisational in nature. Lastly, a VAMP is a repeating musical phrase that is used as an introduction or interlude.