What does a music video do? (purpose)

-Sell the song and invoke a reaction so it leaves you remembering the song.
-To give the listener a better understanding of the song (if the video is narrative).
-To entertain (to show off other talents the musician may have, for example dancing or acting).
-To sell CDs and DVDs to veiwers, creating a memorable visual for the song increases its chance to sell.
-Marketing for the purpose of exposure and expansion of the artists profile.