Teeth whitening kits are products designed to lighten the color of teeth and remove stains. They typically include whitening gels, trays, or strips that are applied to the teeth for a specified period. Many kits use ingredients like hydrogen peroxide or carbamide peroxide to break down stains and achieve a brighter smile. These kits can be purchased over-the-counter or prescribed by a dentist. While they are generally safe for most people, it's important to follow the instructions carefully to avoid tooth sensitivity or gum irritation. Results can vary based on the individual's dental health and the severity of the stains.