An ultracold gas of bosonic atoms at sufficiently low temperature undergoes a phase transition known as Bose-Einstein condensation and becomes essentially a macroscopic quantum system. It is macroscopic both in the sense that on the order of a million atoms may be occupying the same quantum state and in the sense that this system can be hundreds of micrometers or larger in size - large enough to be resolved even with the naked eye. Such a gas is superfluid, and when confined in a ring-shaped trap can support a persistent current, a superflow that is undamped for as long as the gas itself can last in an imperfect vacuum. This flow is the basis for an “atomtronic” closed circuit where the flow of atoms is analogous to the flow of electrons in electronic circuits. The unique opportunities for control and observation offered by atomic gases, along with fluid versions of Josephson junctions, have produced a wealth of interesting results.