Ejaculation is the ejecting of semen (usually carrying sperm) from the male reproductory tract, and is usually accompanied by orgasm. It is usually the final stage and natural objective of sexual stimulation, and an essential component of natural conception. (Quoted from Wikipedia, the free encyclopedia)
The vagina is a tube that extends between the cervix and the vulva where it opens the legs of the human female. The vagina is extremely elastic and the baby is delivered normally through the vagina.
During sexual intercourse, sperm are ejaculated from your partner's penis into your vagina. In one ejaculation, there may be more than 300 million sperm.
The sperm are ejaculated into the vagina at a speed of up to 500 cm (200 inches) per second.
Once inside your body, the sperm begin the hard work of locating your egg and fertilising it.