Soap is a solid, powdered or liquid substance made with the purpose of cleaning the surface of some dirty material, and which is made by cooking until it melts a mixture of vegetable or animal fats and oils.

The concern of the human being for the cleanliness of the body and its environment has always been known, that is why the manufacture of soap is one of the oldest chemical synthesis. For example, the Germanic tribes of the time of Caesar boiled goat tallow with potash (potassium hydroxide) obtained by leaching the ashes of wood fires.

Modern chemistry has refined the raw materials as well as the technique, but soap making is basically the same as it was two thousand years ago: a fatty acid (of plant or animal origin) is combined with a solution of water and an alkali ( sodium or potassium hydroxide) thus producing soap and glycerin, this reaction is known as saponification.

The fatty acids required for soap making are obtained from tallow, fat and fish oils. Soap can vary in its composition and in the method of its processing.

Hard soaps are made with oils and fats that contain a high percentage of saturated acids, which are saponified with sodium hydroxide, and are used to wash objects and clothes. Soft soaps are produced from linseed oil, cottonseed oil and fish oil, and saponified with potassium hydroxide, these are mainly liquid soaps for hygiene (shampoo, gels, soap and shaving foam, etc.).

Toilet soaps are made from vegetable oils such as coconut, palm and olive. These oils undergo a refining process to remove any traces of caustic soda that they may contain, as they would damage the skin.

The dispersing power of soap allows it to eliminate the solid particles that make up dirt, keeping them in suspension, so that they can be immediately swept away by the water during the bath.

In general, soaps have evolved throughout history in different formats and varieties, they have even diversified in styles according to the characteristics of each skin and the needs it requires. Whatever the soaps are, they fulfill their function of cleaning the dirt particles.

Today, soap is also used as a bathroom decorator, there are various forms and decoration designs for it, some even have excellent fragrances to permeate the environment.