Libido is the term that the noted founder of psychoanalysis, Sigmund Freud, used to label the sexual drive or sexual instinct. He noted that the sexual drive is characterized by a gradual buildup to a peak of intensity, followed by a sudden decrease of excitement.

As he studied this process in his patients, Freud concluded that various activities like eating and drinking, as well as urination and defecation share this common pattern. Consequently, he regarded these behaviors as sexual or libidinous as well.

Freud also became interested in the development of the libido, which he saw as the basic and most powerful human drive. He believed that the development of the libido involved several distinct and identifiable stages.

Learn more about Freud's theory on how libido develops in the next section.