A tampon is a mass of cotton or rayon or a mixture of the two inserted into a body cavity

Body cavity

By the broadest definition, a body cavity is any fluid-filled space in a multicellular organism. However, the term usually refers to the space located between an animal’s outer covering and the outer lining of the gut cavity, where internal organs develop...

 or wound

Wound

A wound is a type of injury in which skin is torn, cut or punctured , or where blunt force trauma causes a contusion . In pathology, it specifically refers to a sharp injury which damages the dermis of the skin.-Open:...

 to absorb bodily
fluid. The most common type in daily use (and the topic of the remainder of this article) is designed to be inserted into the vagina

Vagina

The vagina is a fibromuscular tubular tract leading from the uterus to the exterior of the body in female placental mammals and marsupials, or to the cloaca in female birds, monotremes, and some reptiles. Female insects and other invertebrates also have a vagina, which is the terminal part of the...

 during menstruation

Menstruation

Menstruation is the shedding of the uterine lining . It occurs on a regular basis in sexually reproductive-age females of certain mammal species. This article focuses on human menstruation.-Overview:...

 to absorb the flow of menstrual fluid. Several countries—including the United States

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

, under the banner of the Food and Drug Administration

Food and Drug Administration

The Food and Drug Administration is an agency of the United States Department of Health and Human Services, one of the United States federal executive departments...

 (FDA)—regulate tampons as medical devices.