Flatulence is a mixture of gases that are produced by symbiotic bacteria and yeasts living in the gastrointestinal tract of mammals, and aerosolized particles of feces, and it is released under pressure through the anus with a characteristic sound and odor. Flatulence in its verb form is called flatulation or to flatulate is known colloquially as farting, but some people find the word fart offensive and will use a euphemism as an alternative. Most animals, birds, fishes and insects also fart.