In the past, it wasn't possible for the general public to go out and purchase these products in stores, the only way you could have your teeth whitened was through a dentist, who would charge you a considerable amount of money.
The vast majority of people use home teeth whitening products in order to get rid of stains on their teeth caused by certain foods, alcohol and nicotine. It's usually very easy for you to apply it to your teeth and they generally have no noticeable side effects.
There are several methods that you can use to whiten your teeth, one of those methods is the whitening gel. With the whitening gel you can expect visible results within 3 weeks.
Other whitening products are the brush-on whitening paste. You simply brush your teeth with the paste, as you would with any other paste, only this one contains a whitening formula. You can expect visible results from this within 2 weeks.
The last method is the whitening strips. It's very easy for you to put the strips on and take them off. You can expect visible results within a week, but they can be fairly expensive to maintain.
If you're bothered by not smiling in public or in family photos, or having people talk about your stained teeth, then a specialised teeth whitening product might be what you need.