A body piercing, which is a form of body modification, is the practice of puncturing or cutting a part of the human body, creating an opening in which jewelry may be worn, or where an implant could be inserted. The word piercing can refer to the act or practice of body piercing, or to an opening in the body created by this act or practice. It can also, by metonymy, refer to the resulting decoration, or to the decorative jewelry used. Piercing implants alter the body and/or skin profile and appearance (e.g. golden threads installed subdermal, platinum, titanium or medical grade steel subdermal implants).

Ear piercing and nose piercing have been particularly widespread and are well represented in historical records and among grave goods. The oldest mummified remains ever discovered had earrings, attesting to the existence of the practice more than 5,000 years ago. Nose piercing is documented as far back as 1500 BCE. Piercings of these types have been documented globally, while lip and tongue piercings were historically found in African cultures and many more but is actually from the Middle East. Nipple and genital piercing have also been practiced by various cultures, with nipple piercing dating back at least to Ancient Rome while genital piercing is described in Ancient India c. 320 to 550 CE. The history of navel piercing is less clear. The practice of body piercing has waxed and waned in Western culture, but it has experienced an increase in popularity since World War II, with sites other than the ears gaining subcultural popularity in the 1970s and spreading to the mainstream in the 1990s.

The reasons for piercing or not piercing are varied. Some people pierce for religious or spiritual reasons, while others pierce for self-expression, for aesthetic value, for sexual pleasure, to conform to their culture or to rebel against it. Some forms of piercing remain controversial, particularly when applied to youth. The display or placement of piercings have been restricted by schools, employers and religious groups. In spite of the controversy, some people have practiced extreme forms of body piercing, with Guinness bestowing World Records on individuals with hundreds and even thousands of permanent and temporary piercings.

Contemporary body piercing practices emphasize the use of safe body piercing materials, frequently utilizing specialized tools developed for the purpose. Body piercing is an invasive procedure with some risks, including allergic reaction, infection, excessive scarring and unanticipated physical injuries, but such precautions as sanitary piercing procedures and careful aftercare are emphasized to minimize the likelihood of encountering serious problems. The healing time required for a body piercing may vary widely according to placement, from as little as a month for some genital piercings to as much as two full years for the navel. Some piercings may be more complicated, leading to rejection.

Body adornment has only recently become a subject of serious scholarly research by archaeologists, who have been hampered in studying body piercing by a scarcity of primary sources. Early records rarely discussed the use of piercings or their meaning, and while jewelry is common among grave goods, the deterioration of the flesh that it once adorned makes it difficult to discern how the jewelry may have been used.

The modern record has been also distorted by the 20th-century inventions of piercing enthusiast Doug Malloy. In the 1960s and 1970s, Malloy marketed contemporary body piercing by giving it the patina of history. His pamphlet Body & Genital Piercing in Brief included such commonly reproduced urban legends as the notion that Prince Albert invented the piercing that shares his name in order to diminish the appearance of his large penis in tight trousers, and that Roman centurions attached their capes to nipple piercings. Some of Malloy's myths were reprinted as fact in subsequently published histories of piercing.

Ear piercing has been practiced all over the world since ancient times, and there is considerable written and archaeological evidence of the practice. Mummified bodies with pierced ears have been discovered, including the oldest mummified body discovered to date, the 5,300-year-old Ötzi the Iceman, which was found in a glacier in Italy. The mummy had an ear piercing 7–11 mm (0.28–0.43 in) in diameter. The oldest earrings found in a grave date to 2500 BCE. These were located in the Sumerian city of Ur, home of the Biblical patriarch Abraham. Earrings are mentioned in the Bible. In Genesis 35:4, Jacob buries the earrings worn by members of his household along with their idols under a tree. In Exodus 32, Aaron makes the golden calf from melted earrings. Deuteronomy 15:12–17 dictates ear piercing for a slave who chooses not to be freed. Earrings are also referenced in connection to the Hindu goddess Lakshmi in the Vedas. Earrings for pierced ears were found in a grave in the Ukok region between Russia and China dated between 400 and 300 BCE.

Among the Tlingit people of the Pacific Northwest of America, earrings were a sign of nobility and wealth, as the placement of each earring on a child had to be purchased at an expensive potlatch. Earrings were common in the Eighteenth dynasty of Egypt (1550–1292 BCE), generally taking the form of a dangling, gold hoop. Gem-studded, golden earrings shaped like asps seem to have been reserved for nobility. The ancient Greeks wore paste pendant earrings shaped like sacred birds or demigods, while the women of ancient Rome wore precious gemstones in their ears.