The Batwing was Batman's aircraft and main mode of aerial transportation.
Batman used the Batwing when it was necessary to travel longer distances than he could in the Batmobile, to counter airborne threats, or to ambush enemies from above.
The Batwing was redesigned at least twice in Batman's career. The original had a claw that could be used offensively or for rescue operations. The second Batwing had missile capability. Both Batwings were capable of vertical take-off and landing.
The (first) Batwing was designed by Shayne Poindexter and Bruce Timm, and specifically modeled to resemble the Batwing as it appeared in the 1989 Batman movie. The use of the term "Batwing" (as opposed to the conventional "Batplane") was also carried over from the Tim Burton movie.