Catalysis: The process by which a substance speeds up a chemical reaction without being consumed or altered in the process. Substances that can accomplish this remarkable feat are termed catalysts and are of immense importance in chemistry and biology.
All enzymes are catalysts that expedite the biochemical reactions necessary for life. The enzymes in saliva, for example, accelerate the conversion of starch to glucose, doing in minutes what would otherwise take weeks.
The word "catalyst" was introduced into science by the great Swedish chemist Jons Jakob Berzelius (1779-1848) who also determined the atomic and molecular weights of thousands of substances, discovered several elements including selenium, first isolated silicon and titanium, and created the present system of writing chemical symbols and reactions.