The motion of idealized inextensible strings is discussed. The equations of motion are analyzed for closed-loop configurations, free of body forces and open hanging strings whirling under gravity. The latter give rise to an interesting non-linear eigenvalue problem describing a spectrum of whirling modes that is amenable to numerical investigation by using the shooting method for two-point boundary value problems. The spectrum is compared with that for small amplitude excitations in both fixed and rotating vertical plane through the suspension point. The results provide a useful theoretical background for an analysis of a laboratory exploration of whirling chains.