A haploid reproductive cell. Sperm cells and ova are gametes, and they differ from somatic cells in their chromosome number.
Gametes only have one set of chromosomes.
Thus, the haploid number for humans is 23. The diploid number is restored when two haploid gametes unite in the process of fertilization. Sexual intercourse allows a haploid sperm cell from the father to reach and fuse with an ovum from the mother, producing a diploid zygote.