Semen is a fluid produced by the male reproductive system that contains sperm cells. It plays a crucial role in reproduction, as sperm are necessary for fertilizing an egg from a female. Semen is made up of various components, including water, proteins, and sugars, which provide energy and support for the sperm. When a male ejaculates, semen is released from the penis and can enter the female's vagina. If a sperm cell successfully meets and fertilizes an egg, it can lead to pregnancy. Understanding semen is important for discussions about sexual health and reproduction.