The Black Kite is not generally black at all but dark brown, with a light grey head characteristic of kites; it lacks the rufous-brown plumage of its larger cousin, the Red Kite. Black Kites are found over much of Europe (not UK except rare migrants or feral) and Asia. They generally eat insects and carrion/refuse with some small live prey.
In flight the tail is wedge-shaped or slightly concave but less-forked than that of the Red Kite.
Although kites have feathered legs, the legs are slender, unlike the thick trousered legs of eagles . . .
. . . which assists the kites with their extreme agility in flight.
All above are nominal subspecies European Black Kite M. m. migrans which spend northern summer in Eurasia and northern winter in Africa.
Those above with the characteristic kite under-wing and forked tail are the Black-eared Kite M. m. lineatus from Siberia/east Central Asia to Southeast Asia. Some treat it as a full separate species.