Circumcision is a procedure that removes the foreskin from the human penis. In the most common form of the operation, the foreskin is extended with forceps, then a circumcision device may be placed, after which the foreskin is excised. Topical or locally injected anesthesia is generally used to reduce pain and physiologic stress. Circumcision is generally electively performed, most commonly done as a form of preventive healthcare, as a religious obligation, or as a cultural practice. It is also an option for cases of phimosis, other pathologies that do not resolve with other treatments, and chronic urinary tract infections (UTIs). The procedure is contraindicated in cases of certain genital structure abnormalities or poor general health.

Circumcision is associated with reduced rates of sexually transmitted infections and urinary tract infections. This includes decreasing the incidence of cancer-causing forms of human papillomavirus (HPV) and significantly reducing HIV transmission among heterosexual men within high risk populations. The World Health Organization (WHO) and UNAIDS recommend circumcision as part of a comprehensive HIV transmission program in areas with high endemic rates of HIV. The WHO does not recommend circumcision for HIV prevention in men who have sex with men; effectiveness of using circumcision to prevent HIV in the developed world is unclear. Neonatal circumcision also decreases the risk of penile cancer. Complication rates are higher when the procedure is performed on older people. A 2010 review found circumcisions performed by medical providers to have a typical complication rate of 1.5% for babies and 6% for older children, with few cases of severe complications. Bleeding, infection, and the removal of either too much or too little foreskin are the most common acute complications. Meatal stenosis is the most common long term complication. Major medical organizations hold variant perspectives on the prophylactic efficacy of the elective circumcision of minors. The WHO, UNAIDS, and American medical organizations take the position that it carries prophylactic health benefits which outweigh small risks, while European medical organizations generally hold the belief that in these situations its medical benefits are not counterbalanced by risk.

Prophylactic circumcision originated in England during the 1850s, becoming established as a way to prevent sexually transmitted infections. Beyond use as a prophylactic or treatment option in healthcare, circumcision plays a major role in many of the world's cultures and religions, most prominently Judaism and Islam. Circumcision is among the most important commandments in Judaism. Historically, campaigns of Jewish persecution have included bans on the practice as a means of forceful assimilation, conversion, and ethnocide. Variant medical, cultural, religious, and ethical views have led to a widely diverging incidence and prevalence within polities. It is widespread in Australia, Canada, the United States, South Korea, New Zealand, most of Africa, and parts of Asia. It is relatively rare for non-religious reasons in parts of Southern Africa, Latin America, Europe, and parts of Asia. The origin of circumcision is not known with certainty; the oldest documentation comes from ancient Egypt.