Latin for "in glass", in vitro means that a cell or other component has been removed from their biological surroundings and isolated in order to allow a different analysis than can be done with it located inside of the organism.

Due to the nature of complex organisms such as humans, the value of removing a cell is the ability to explore its basic function, which contributes to greater understanding of its larger function.

Most commonly, in vitro is known for its role in in vitro fertilization, which combines sex cells outside of the body and then implants the resulting embryo into the uterus of the mother.