Graphene is an allotrope (structural configuration) of carbon atoms, in the form of one-atom-thick sheets of carbon atoms that are densely packed in a honeycomb lattice. Graphene is most easily visualized as an atomic-scale chicken wire made of carbon atoms and their bonds.
The crystalline or ‘flake’ form of graphite consists of many graphene sheets stacked together. Graphene is the basic structural element of some carbon allotropes including graphite, charcoal, carbon nanotubes and fullerenes.
The Daily Omnivore 