Endorphins (“endogenous morphine”) are endogenous opioid inhibitory neuropeptides. They are produced by the central nervous system and pituitary gland. The term implies a pharmacological activity (analogous to the activity of the corticosteroid category of biochemicals) as opposed to a specific chemical formulation. It consists of two parts: endo- and -orphin; these are short forms of the words endogenous and morphine, intended to mean “a morphine-like substance originating from within the body”. The class of endorphin compounds includes α-endorphin, β-endorphin, γ-endorphin, α-neo-endorphin, and β-neo-endorphin. The principle function of endorphins is to inhibit the transmission of pain signals; they may also produce a feeling of euphoria very similar to that produced by other opioids.