Factors that determine variations and trends in sexual behaviour are environmental and include shifts in poverty, education, and employment; demographic trends such as the changing age structure of populations and the trend towards later marriage; increased migration between and within countries; globalisation of mass media; advances in contraception and access to family-planning services; and public-health HIV and sexually transmitted disease prevention strategies.
Sexual activity (sexual function) in humans is an instinctive form of physical intimacy. It may be performed for the purposes of biological reproduction, spiritual transcendence, expressing affection, and/or for pleasure and enjoyment (known in this context as “sexual gratification”). The desire to have sex is one of the basic drives of human behavior. Every sexually-reproductive animal species, and every human culture, has a range of conduct used in courtship, intimacy, and sexual activity.
Human sexual behavior is therefore the behaviors that human beings use when seeking sexual or relational partners, gaining approval of possible partners, forming relationships, showing affection, and mating.
It covers at least two major areas: anthropology (common or accepted practices across different cultures), and informational (background which is useful to individuals who may be engaged in, or considering, sexual activity).
— The Lancet