Graphene, a monolayer of sp2-bonded carbon atoms, is not only the basis for graphite but also a new material for various applications in the field of micro- and optoelectronics. Although graphene or single layers of graphite have been subject of research since the 1960s, the special and unique properties of this material have become more and more popular only after 2004. This was mainly pushed forward by the pioneering work of Andre Geim and Konstantin Novoselov who received the Nobel Prize in Physics in 2010. Within the last years the excellent and unique electronic, optical, thermal and mechanical characteristics of graphene were systematically analyzed and explored, making this material ideally suited for various applications.