Undoped graphene isn&#xE2;&#x80;&#x99;t a metal, semiconductor, or insulator but a semimetal, whose unusual properties include electron-electron interactions between particles widely separated on graphene&#xE2;&#x80;&#x99;s honeycomb lattice - here suggested by an artist&#xE2;&#x80;&#x99;s impression of Feynman diagrams of such interactions. Long-range interactions, unlike those that occur only over very short distances in ordinary metals, alter the fundamental character of charge carriers in graphene. | Photo Courtesy of Caitlin Youngquist, Berkeley Lab Public Affairs