A bar of soap is a solid cleansing product that is typically used for personal hygiene. It is made by combining fats or oils with an alkali, such as sodium hydroxide, through a process called saponification. The resulting mixture is then molded into a solid form, often rectangular in shape, and left to harden. When used with water, the bar of soap produces lather or foam that helps to remove dirt, oil, and bacteria from the skin. It is a common household item found in bathrooms and is available in various scents, sizes, and formulations to cater to different skin types and preferences.