G324 - The Purpose Of A Music Video

Music videos have several different purposes:

1: Publicity - To advertise the artists new single and/or new album that they will be releasing.

2: Money - Music videos (much like the music itself) can be bought on Itunes so that people can watch the video on the move.

3: Portraying the artists image - For example, an artist may completely change their style and they can use their new music video to demonstrate this change and to introduce their fans to their new image. A good example of this is Miley Cyrus's "We Can't Stop" as she has a completely new look from her older music videos

"Who Owns My Heart" - Miley Cyrus

2010

"We Can't Stop" - Miley Cyrus
2013

4: Product placement - Music videos often use product placement (showing a certain brand in the video) This will make the artist more money as companies will pay to have their product shown as a way of advertisement.
For example in Avril Lavignes song "What The Hell" There's a close-up of a Sony Ericsson mobile phone -

5: Telling the story - Music videos are often used to visually tell the story/the meaning of the lyrics in the song.

6: Promotion - Music videos can be used to promote a film, by using clips of the film the song is being used in, in the video. for example Muse "Neutron Star Collision" was a song written by Muse for The Twilight Saga Breaking Dawn Part 1 film, and the music video included clips of the film.