These contain polishing agents that help remove everyday, light stains which are also known as surface stains. They don't have bleach and are not as powerful or as expensive as hydrogen peroxide based teeth whitening products. The latter is a bleaching chemical that helps lighten surface stains along with more stubborn, inner stains on the enamel. Such hydrogen peroxide based whitening products are applied orally, with a brush to the teeth enamel. Such products are available in 2 forms - the first is gel which is applied for a restricted number of days till you can see the desired effect on your teeth.
The results of the gel normally last for a few months after which, your teeth will begin to yellow and stain as before. Of course, you may use natural teeth whitening remedies to continue the effect of this gel for a slightly longer period of time. Gels usually don't cost more than $20 or so but they must be applied at least twice a day.
Teeth whitening strips are another option costing about $50 and containing peroxide. You may also consider the more expensive and more permanent procedures like in-office whitening and tray- based whitening.