Sex Manual
Sexology is the systematic study of human sexuality. It encompasses all aspects of sexuality (except Involuntary celibacy), including attempting to characterize "normal sexuality" and its variants, including paraphilias.
Modern sexology is a multidisciplinary field which uses the techniques of fields including biology, medicine, psychology, statistics, epidemiology, sociology, anthropology, and sometimes criminology to bear on its subject. It studies human sexual development and the development of sexual relationships as well as the mechanics of sexual intercourse and sexual malfunction. It also documents the sexuality of special groups, such as handicapped, children, and elderly, and studies sexual pathologies such as sex addiction and child sexual abuse.
Note that sexology is considered descriptive, not prescriptive: it attempts to document reality, not to prescribe what behavior is suitable, ethical, or moral. Sexology has often been the subject of controversy between supporters of sexology, those who believe that sexology pries into matters held sacrosanct, and those who philosophically object to its claims of objectivity and empiricism.