Fertilization takes occurs in the fallopian tubes, where the sperm cell and the egg cell unite and produce a zygote (diploid).
The zygote will proceed down the fallopian tube and into the uterine lining, which is known as implantation, and the zygote implantation is known as a blastocyst.
When sperm and ovum come into contact, a change in the ovum's membrane (zona pellucida) occurs, which prevents subsequent sperms from entering.