Bat-insignia

The Bat-Insignia (also known as the Bat-Symbol or the Batman Emblem) is the seal that represents Batman. It is considered one of the most iconic and recognizable symbols of all time. Over the years, the symbol has been redesigned to accompany the many reiterations of Batman. In it's many variations, it is in the shape of a highly-stylized bat with it's wings open. The seal is also typically featured in almost every facet of Batman including the Batsuit and the Bat-Signal.

Classic Batman, 1940s
The Bat-Insignia inspired by the original Batman in his Detective Comics debut resembled a pair of bat wings with batman's head on top.

Nolan Films
For the Nolan trilogy, the seal was redesigned, this time abandoning the "circular wing" forms.