The sexes are the two distinct types of organisms that produce gametes, male and female. The term is most often used to refer to humans, although it can also be applied to other animals and plants. Male and female gametes fuse during fertilization to produce a zygote that develops into an offspring with a unique combination of genes from each parent.
Sexual reproduction is essential for the continuation of many species, including humans. The process of meiosis, in which chromosomes are shuffled between parents before being passed on to offspring, creates variation within a population that can help ensure its survival in the face of changing environmental conditions. Additionally, sexual selection—the idea that individuals with certain traits are more likely to mate and pass those traits on to their offspring—can result in the evolution of new species or even help existing ones adapt to new environments.
Despite its importance, sex is not always necessary for reproduction. Some species can reproduce through asexual means, such as by producing clones of themselves or budding off new individuals from existing ones. Asexual reproduction is often faster and simpler than sexual reproduction, but it comes with the cost of reduced genetic diversity. As a result, asexual populations are generally less resilient to change than sexually reproducing ones and are more likely to go extinct if conditions shift too much.