You might have three different types of soap in your bathroom: hand, body and face. But are all of those soaps really necessary? Historically, soap was simply a fat (often an animal byproduct such as lard or beef tallow) cooked with an alkali (such as potash) to create a chemical reaction known as saponification. This resulted in a foaming substance -- either liquid or solid, depending on the alkali -- that helped remove dirt and grime.
Today's soap doesn't always meet the traditional soap criteria due to the use of modern ingredients like petroleum-based detergents and synthetic surfactants. However, many companies still sell soaps made with natural oils, usually replacing the animal fat with a vegetable-based oil like olive, palm or coconut.
The truth is, you could really use a single soap to wash all the parts of your body; there's really no need for three of them. While antibacterial soaps for hand-washing have become popular, many researchers believe that constant use could actually be harmful, as they can kill off good bacteria and also create bacteria that are resistant to antibiotics. The real benefit in hand-washing may come in the scrubbing motion, which physically removes bacteria.
So if you're thinking of going with just one soap, what kind should you chose? Consider a castile soap. This firm, white olive-oil-based soap was first made in the Castile region of Spain in the early 1600s. An extra step in the process, including the addition of brine, creates a pure soap suitable for use all over your body. It won't dry out or harm sensitive skin, either. Most companies that make castile soaps use essential oils like lavender, rosemary or eucalyptus to scent them, so you don't have to give up the nice smell that you get from your current body wash. As a bonus, castile soap is usually much less expensive, especially if you buy it in liquid, concentrated form.