Enzymes are biological catalysts and are produced by living organisms to speed up the biochemical reactions they need in order to survive.
Different enzymes require different conditions to work at their highest activity (known as the optimal conditions), but most require a temperature close to 37°C (human body temperature). If temperatures exceed the optimal temperature, the enzyme can become denatured and stop working properly.
Enzymes are often more effective than any non-biological alternatives, and so they are used commercially to speed up a number of different reactions. This includes uses in: