Meiosis I is the first stage of a special type of cell division that produces gametes, which are the reproductive cells like sperm and eggs. During this phase, a single cell divides into two cells, each with half the number of chromosomes. This reduction is crucial for maintaining the correct chromosome number when fertilization occurs. In Meiosis I, homologous chromosomes, which are pairs of similar chromosomes from each parent, line up and exchange genetic material in a process called crossing over. This mixing of genes increases genetic diversity, making each gamete unique and contributing to the variation seen in offspring.