Human sexuality is how people experience and express themselves as sexual beings. Human sexuality has many aspects. Biologically, sexuality refers to the reproductive mechanism as well as the basic biological drive that exists in all species and can encompass sexual intercourse and sexual contact in all its forms. There are also emotional or physical aspect of sexuality, which refers to the bond that exists between individuals, which may be expressed through profound feelings or emotions, and which may be manifested in physical ormedical concerns about the physiological or even psychological aspects of sexual behaviour.Sociologically, it can cover the cultural, political, and legal aspects; and philosophically, it can span the moral, ethical, theological, spiritual or religious aspects.

Recent studies on human sexuality have highlighted that sexual aspects are of major importance in building up personal identity and to social evolution of individuals:

“Human sexuality is not simply imposed by instinct or stereotypical conducts, as it happens in animals, but it is influenced both by superior mental activity and by social, cultural, educational and normative characteristics of those places where the subjects grow up and their personality develops. Consequently, the analysis of sexual sphere must be based on the convergence of several lines of development such as affectivity, emotions and relations”.

The biology of human sexuality examines the influence of biological factors, such as organic and neurological response, heredity, hormones, and sexual dysfunction; it examines the basic functions of reproduction and the physical means to carry it out. The biological perspective helps to analyze the factors, and ultimately aids in understanding them and using them to deal with sexual problems.

Sex as exercise burns calories to produce health benefits. Sex also relieves stress, boosts theimmune system with higher levels of immunoglobulin A, improves cardiovascular health, increasesself-esteem, improves intimacy, reduces pain by production of the hormone oxytocin, reduces the risk of prostate cancer, strengthens pelvic muscles, and promotes good sleep. Sex also improves the sense of smell and urinary bladder control.

Sexual behavior can be a disease vector. Safe sex is a relevant harm reduction philosophy.