Pop stars are seen and paid more when they promote a product.
Some fans may see this as "selling-out". It can mean that their sponsor company sells a lot more of what it makes as people see their stuff as cool.
One the big pop sponsors is Pepsi who have done deals with:
- Ms Dynamite
- Beyonce Knowles
- Gareth Gates
- Britney Spears
- S Club
- Robbie Williams
- Spice Girls
- The Corrs
- Michael Jackson who earned a reported £3.4m ($5m) for his Pepsi deal in 1984.
- Madonna was dropped from an $8m Pepsi campaign over allegedly blasphemous video for her Like a Prayer single.
S Club have also been sponsored by BT, Sugar Puffs and Cadbury's.