Meiosis I is the first stage of meiosis, a type of cell division that reduces the chromosome number by half. It occurs in germ cells to produce gametes, such as sperm and eggs. During this phase, homologous chromosomes pair up and exchange genetic material through a process called crossing over, increasing genetic diversity. The process consists of several steps: prophase I, where chromosomes condense and pair up; metaphase I, where these pairs align at the cell's center; anaphase I, where homologous chromosomes are pulled apart; and telophase I, where the cell divides into two daughter cells, each with half the original chromosome number.