Meiosis is a cell division process that produces four haploid cells from one diploid cell. It involves two rounds of division called Meiosis I and Meiosis II. In Meiosis I, homologous chromosomes pair up and may exchange genetic material through crossing over. The homologous chromosomes then separate, reducing the chromosome number by half. Meiosis II then divides the cells again without further chromosome replication or crossing over, resulting in four haploid cells each with half the number of chromosomes of the original cell. This process is important for sexual reproduction as it generates genetic diversity through independent assortment and crossing over.