Biotechnology is technology based on biology, especially when used in agriculture, food science, and medicine. The UN Convention on Biological Diversity has come up with one of many definitions of biotechnology: "Biotechnology means any technological application that uses biological systems, living organisms, or derivatives thereof, to make or modify products or processes for specific use." Traditional pharmaceutical drugs are small chemicals molecules that treat the symptoms of a disease or illness - one molecule directed at a single target.

Biopharmaceuticals are large biological molecules known as proteins and these target the underlying mechanisms and pathways of a malady ; it is a relatively young industry. They can deal with targets in humans that  are not accessible with traditional medicines. A patient typically is dosed with a small molecule via a tablet while a large molecule is typically injected. Small molecules are manufactured by chemistry but large molecules are created by living cells: for example, - bacteria cells, yeast cell, animal cells.

Modern biotechnology is often associated with the use of genetically altered microorganisms such as E. coli or yeast for the  production of substances like insulin or antibiotics. It can also refer to transgenic animals or transgenic plants, such as  Bt corn. Genetically altered mammalian cells, such as Chinese Hamster Ovary (CHO) cells, are also widely used to manufacture  pharmaceuticals. Another promising new biotechnology application is the development of plant-made pharmaceuticals.

Biotechnology is also commonly associated with landmark breakthroughs in new medical therapies to treat diabetes, Hepatitis  B, Hepatitis C, Cancers, Arthritis, Haemophilia, Bone Fractures, Multiple Sclerosis, Cardiovascular as well as molecular  diagnostic devices than can be used to define the patient population. Herceptin, is the first drug approved for use with a  matching diagnostic test and is used to treat breast cancer in women whose cancer cells express the protein HER2.

Biotechnology in one form or another has flourished since prehistoric times. When the first human beings realized that they could plant their own crops and breed their own animals, they learned to use biotechnology. The discovery that fruit juices fermented into wine, or that milk could be converted into cheese or yogurt, or that beer could be made by fermenting solutions of malt and hops began the study of biotechnology. When the first bakers found that they could make a soft, spongy bread rather than a firm, thin cracker, they were acting as fledgling biotechnologists. The first animal breeders, realizing that different physical traits could be either magnified or lost by mating appropriate pairs of animals, engaged in the manipulations of biotechnology.