(a) Kitaev’s model describes a two-dimensional system of spins S=1/2 on a honeycomb lattice interacting through a strongly anisotropic exchange interaction. Under certain conditions, the system is a quantum spin liquid (QSL), in which the spin arrangement is constantly in flux. (b) Phase diagram for a QSL. The model predicts a gapped and a gapless phase. The latter should host propagating Majorana fermions, whose signatures could be measured, according to the work of Knolle et al.