Bats (Chiroptera) are the worlds only group of mammals that have wings. Although some other groups of mammals, such as flying lemurs, are able to glide using skin membranes, only bats are capable of true flight. Bats' wings are formed by a skin membrane (called the patagium) which extends from its long fingers to the sides of its body. Its skeleton is further modified to enable flight, with fused vertebrae and a strong sternum to anchor some of the muscles used in flight.
Bats inhabit tropical and temperate regions. They are absent from polar regions.