The term "polygraph" literally means "many writings". The name refers to the manner in which selected physiological variables are simultaneously recorded. Using specialized components, a typical polygraph collects physiological data from three signals generated from the human body. Respiratory activity is recorded by convoluted rubber tubes that are placed over the examinee's chest and abdominal areas. Electrodermal or sweat gland activity is recorded by two small sensors attached to the fingers. Cardiovascular activity is recorded by a blood pressure cuff or similar device. Together these variables provide continual data regarding an individual's sympathetic and parasympathetic nervous system which are part of the autonomic division of the peripheral nervous system which controls physiological actions and reactions.

In 1917, the first polygraph examination was used for counterintelligence work during World War I. The FBI began using polygraph examinations in 1938. Polygraph systems and research have advanced dramatically throughout the last 70 years and in 1986 the introduction of computerized polygraph systems began which has led to today's advanced state of the art systems.

At the federal level alone, the polygraph is used extensively in counter-intelligence, counter-terrorism, and counter-narcotics programs in addition to criminal investigations, intelligence operations, presidential protection and nuclear materials containment. There are at least 68 countries world wide where the polygraph is used for similar applications. In the private sector, polygraph is used extensively by individuals, families, therapists, attorneys, courts, business and many other entities.