Athlete's foot is caused by a fungus that grows on or in the top layer of skin. Fungi (plural of fungus) grow best in warm, wet places, such as the area between the toes.
Athlete's foot spreads easily. You can get it by touching the toes or feet of a person who has it. But most often, people get it by walking barefoot on contaminated surfaces near swimming pools or in locker rooms. The fungi then grow in your shoes, especially if your shoes are so tight that air cannot move around your feet.
Athlete's foot can make your feet and the skin between your toes burn and itch. The skin may peel and crack. Your symptoms can depend on the type of athlete's foot you have. Read more about athlete's foot.