Soap is primarily made from fats or oils, which can be derived from plants or animals. These fats undergo a chemical process called saponification, where they react with an alkali, usually sodium hydroxide or potassium hydroxide. This process creates glycerin and soap, which helps to cleanse the skin by trapping dirt and oils. In addition to fats and alkali, many soaps include fragrances for scent, colorants for visual appeal, and moisturizers like glycerin or shea butter to nourish the skin. Some soaps may also contain essential oils for added benefits, such as tea tree oil for its antibacterial properties.