A diploid cell contains both sets of homologous chromosones. Homologous chromosomes are sets of chromosomes from both the mother and father that pair together inside a cell. Human diploid cells consist of 46 chromosomes.
The chromosomes pair with each other during a process that is known as meiosis, by which a cell undergoes division in order to undergo sexual reproduction. These cells separate to form haploid cells, or cells which only have one set of chromosomes. They can then exchange genetic material by means of crossing over. The division occurs in two stages, with meiosis I being the stage in which cells are diploid.