Biotechnology is the use of biological organisms, systems, or processes, to make or modify products. Biotechnology dates from the first fermented drinks, and for thousands of years man has used microorganisms, notable yeasts and molds, to make food, drugs, dyes, fertilizers, etc.

As their understanding of microbes and molecular biology has grown, biotechnologists have been able to increase the output of traditional microorganisms by creating an environment in which they multiply quickly and can be used for large-scale production. Sometimes, rather than the whole microbe, they use a part of it, particularly enzymes which will perform some subsequent chemical conversion. Where there is no known enzyme or microbe that manufactures a substance naturally, the techniques of genetic engineering can be applied to create new strains. For example, foreign genes can be inserted into bacteria to endow them with novel characteristics and to induce them to synthesize certain materials. The biotechnological application of genetic engineering requires four main stages: isolating the required gene; inserting the gene into the bacteria; inducing the bacteria to start synthesizing the product; and harvesting that product. Production generally involves fermentation, one of man's oldest technologies.