Genetics, the study of the biological mechanisms by which an organism's traits are passed from generation to generation. These mechanisms involve complex molecules that constitute an organism's genetic material. This material is made up of a large number of subunits called genes.

The general study of the transmission of traits is known as heredity. Genetics is concerned not only with the transmission of traits, but also with other characteristics of genetic material. Genetics has become a science central to medicine, biology, and the study of evolution. Discoveries within genetics led to the development of the field of moecular biology.

A number of areas of study have developed within genetics. Population genetics studies the occurrence of different genes in different groups of people. Behavioral genetics looks at the effects of genes on traits or behavioral patterns. Statistical genetics develops and applies statistical methods to analyze genetic data. Genetic epidemiology looks at genetic influences in the amount and distribution of health and disease in groups of people.

Discoveries in genetics have been applied successfully in a number of fields, including medicine and agriculture. Knowledge about genetic factors in disease is crucial in diagnosing and treating illnesses, and genetics is used in finding ways to fight disease-producing viruses and bacteria. Improved methods of animal and plant breeding owe a great deal to the study of genetics.