A cell with two of each kind of chromosome is said to contain a diploid, or 2n, number of chromosomes. This means that the cell has a complete set of chromosomes, with two copies of each chromosome. In humans, for example, diploid cells have 46 chromosomes, with 23 pairs of chromosomes. This is in contrast to haploid cells, which only have one copy of each chromosome, and gametes, which are haploid cells that are involved in sexual reproduction. The term "allele" refers to different forms of a gene that can exist at a specific location on a chromosome.