Sperm are haploid sex cells of the male. They are also known as spermatozoa. Unlike eggs which are large, non-motile, and generally few in number, sperm are tiny, motile, and produced in huge numbers. While the human sperm length (0.002 in [600 æm]) is relatively great due to its long tail, the volume of an entire sperm, tail and all, is only 1/85,000 of the egg.

Reproduction in humans occurs when the sperm are deposited in the vagina of a female near the cervical opening of the uterus. The haploid sperm move into the uterus and up the Fallopian (uterine) tube where an egg may be encountered. With fertilization, the egg finishes its second meiotic division to become haploid. The haploid sperm and mature egg together form a diploid zygote which is the beginning of a new individual.

The male gonad (testis singular, testes plural; testicle is derived from the diminutive...