Gerbes and stacks are objects of algebraic geometry that were introduced by Grothendieck. The theory of gerbes was developed by Giraud in his study of non abelian cohomology. Recently, physicists have been increasingly interested in the differential geometric aspects of gerbes. The differential geometry of abelian gerbes was developed by many people including Brylinski, Hitchin and Murray for gerbes over manifolds, and Behrend-Xu for gerbes over differential stacks. In this talk, we will give an introduction to differential geometry of non abelian gerbes including connection theory. Our approach is based on Lie groupoid theory.