Meiosis is a type of cell division that produces four genetically unique haploid cells (gametes) from a diploid cell. It involves two rounds of division, meiosis I and meiosis II. During meiosis I, homologous chromosomes pair up and exchange segments of DNA in a process called crossing over, which increases genetic diversity. The homologous chromosomes then separate, and the cell divides. During meiosis II, the sister chromatids separate, and the cell divides again. The end result is four haploid cells, each with half the number of chromosomes as the original cell.