Nuptial gifts are food items or inedible tokens that are transferred to females by males during courtship or copulation. Inedible tokens may include items such as a fragment of leaf or twig, a seed tuft, or a silk balloon. In many species of animals, including birds, insects, and spiders, this takes the form of a food item that is transferred from a male to a female just prior to copulation. This is a behaviour known as courtship feeding. In some species of insects such as katydids, the nuptial gift is packaged with the sperm of the male. The package is an edible spermatophore. These extra nutrients in the sperm are assimilated by the female and are thought to enhance the fitness of the offspring produced, thus increasing the probability that a male passes on its genes. Nuptial gifts may therefore be classified into oral and seminal gifts. Nuptial gifts may also be tokens that do not have any direct value as food but may serve as an indicator of male fitness.