Meiosis is a specialized type of cell division that produces gametes, or sex cells, with half the normal number of chromosomes. It involves two rounds of division to reduce the chromosome number from diploid to haploid. This ensures that fertilization restores the normal chromosome number in offspring. Key aspects of meiosis include homologous chromosome pairing, independent assortment of chromosomes, and crossing over. Errors in meiosis can result in gametes with an abnormal chromosome number and cause conditions like Down syndrome.