Biochemistry is the study of chemical processes within and relating to living organisms. It is a sub-discipline of both chemistry and biology, and it can be divided into three fields: structural biology, enzymology, and metabolism. Biochemistry focuses on understanding the chemical basis that allows biological molecules to give rise to the processes that occur within living cells and between cells, which in turn relates greatly to the understanding of tissues and organs, as well as organism structure and function. Biochemistry has become the foundation for understanding all biological processes and has provided explanations for the causes of many diseases in humans, animals, and plants. Biochemistry is a young science, having been known under that term only since about 1900. Biochemistry is a laboratory-based science that combines biology and chemistry, and biochemists study the structure, composition, and chemical reactions of substances in living systems and their functions and ways to control them. Biochemistry has many subspecialties, such as neurochemistry, bioorganic chemistry, clinical biochemistry, physical biochemistry, molecular genetics, biochemical pharmacology, and immunochemistry. Biochemistry has many applications in medicine, dentistry, veterinary medicine, agriculture, and biotechnology.