Enzymes are biological catalysts, typically proteins, that speed up biochemical reactions within living organisms. They are highly specific, meaning each enzyme usually catalyzes only one or a few types of reactions. Enzymes function under specific conditions of temperature and pH and can be denatured (lose their shape and function) by extreme conditions. Catalysts, on the other hand, are substances that increase the rate of a chemical reaction but are not consumed in the process. They can be inorganic or organic. While some catalysts are specific, many are not as highly specific as enzymes. Catalysts can function over a wider range of conditions and are generally more robust than enzymes.