Since its inception more than 40 years ago, Quantum Optics has made remarkable advances in the exploration of the quantum character of light, including the microscopic control of single atoms and photons. Indeed, laser operation has been has been pushed to the conceptual limit with the realization of a laser that operates with one acrobatic atom. Single, flying photons can now be generated deterministically at the push of a button. Ensembles of atoms can be projected into an entangled quantum state by the "click" of a photodetector. Beyond their fundamental significance, such advances are helping to lay the foundations for the new science of Quantum Information, including for the realization of complex quantum networks.