Graphene is the first example of truly two-dimensional crystals - it's just one layer of carbon atoms [1,2]. It turns out that graphene is a gapless semiconductor with unique electronic properties resulting from the fact that charge carriers in graphene obey linear dispersion relation, thus mimicking massless relativistic particles. This results in the observation of a number of very peculiar electronic properties - from an anomalous quantum Hall effect (QHE) [3,4] to the absence of localization. It also provides a bridge between condensed matter physics and quantum electrodynamics and opens new perspectives for carbon-based electronics.