Chromosomal crossover is a biological process that occurs during meiosis, the type of cell division that produces gametes, such as sperm and eggs. During this process, homologous chromosomes—pairs of chromosomes that are similar in shape and size—exchange segments of genetic material. This exchange increases genetic diversity in offspring by creating new combinations of genes. The crossover typically happens during prophase I of meiosis, where the chromosomes align closely and form structures called chiasmata. This genetic recombination is crucial for evolution and adaptation, as it allows for variation in traits among individuals, contributing to the overall genetic diversity of a population.