Human semen is a fluid produced by the male reproductive system, primarily composed of sperm cells and seminal fluid. The sperm cells are responsible for fertilizing the female egg, while the seminal fluid provides nourishment and a medium for the sperm to travel. Semen is typically ejaculated during sexual intercourse. The production of semen occurs in several parts of the male reproductive system, including the testes, epididymis, and seminal vesicles. Semen plays a crucial role in reproduction, as it carries the genetic material necessary for creating a new individual.