What is the purpose of a music video?

I have researched into this subject and I have found that a music video has can have more than one purpose, for example, a music video can have the purpose to;

one: Entertain 

A music video can just be made for something entertaining for audience members to watch and laugh at, for instance, the music video to 'The Lion Sleeps Tonight' 

The music video does not reflect the lyrics of the song nor does it contain any product placement etc.. meaning that producers decided to create a music video to the well known song for entertainment. 

Two: Promote an artist and/product
A music video can be made in order to sell a product or company that had a lot of influence on the budget of the video, and it also allows the artist his/herself to be known to the public and to get themselves out there.
The music video to 'What the Hell' by Avril Lavigne uses a lot of product placement, mostly for the company 'SONY' she also promotes herself by showing shots of her own perfume and herself using it.



Three: explanation of the songs lyrical meaning/message

Music videos can be used to explain messages in the song so audience members are clear of what the artist/band were trying to convey in their song.
The music video to 'G.U.Y' by Lady Gaga explains in detail how what the song is all about, resulting to an eleven minute video of how she portrays a fallen angel who is then reborn.