Soap - Wikipedia

Soap is a term for any of a number of compounds used primarily in cleansing, usually made by combining a fat with an alkali. Although the term soap continues to be used informally in everyday speech and product labels, in practice nearly all kinds of "soap" in use today are actually detergents, which are less expensive, more effective, and easier to manufacture.

Soaps are useful for cleansing because soap molecules attach readily to both non-polar molecules (such as grease or oil) and polar molecules (such as water). Although grease will normally adhere to skin or clothing, the soap molecules can attach to it as a "handle" and make it easier to rinse away.

The ancient world was generally innocent of soap; the Romans built baths, but did not often use soap in them. According to Pliny the Elder, soap was invented by the ancient Gauls. They did not use it for washing, though; they used it as a pomade to keep their hair shiny.

Historically, soap was often made in the home by mixing animal fats with lye. Because of the caustic[?] lye, this was a dangerous procedure (perhaps more dangerous than any present-day home activities) which occasionally resulted in serious chemical burns[?] or blindness.