Quantum magnets play a key role in the search for novel states of matter: They can display both con-ventional (i.e. symmetry-breaking) and topological forms of order, together with novel types of ele-mentary excitations, with magnetic monopoles in spin ice being a prominent example. This talk will discuss a particularly fascinating class of frustrat-ed magnets, so-called quantum spin liquids, in which large classical degeneracies and quantum effects conspire to produce non-trivial phases. The emergence of fractionalized excitations and artifi-cial gauge fields will be discussed using explicit microscopic models. Physical signatures of these emergent phenomena will be highlighted. Throughout the talk, contact will be made with ex-periments: Candidate spin-liquid materials and key experimental results will be discussed. Finally, connections to cuprate high-temperature super-conductivity will be highlighted.