Teeth whitening strips are thin, flexible plastic strips coated with a whitening gel that contains hydrogen peroxide or carbamide peroxide. They are designed to be applied directly to the teeth for a specified period, usually ranging from 30 minutes to a few hours, depending on the product. These strips aim to remove stains and lighten the color of teeth, providing a brighter smile. Most teeth whitening strips are available over-the-counter and come in various strengths and formulations. Users typically apply them once or twice a day for a week or more, depending on the desired results. It's important to follow the instructions carefully to avoid potential side effects, such as tooth sensitivity or gum irritation.