This paper develops analogies between discrete devices that achieve damping by active and passive means. It describes the simplest models useful for inclusion in larger system design. Lumped-parameter models for representing passive dampers are given, and the similarity to local active feedback is shown. A model for active damper components containing piezoelectrics or similar materials is developed for force feedback compensation. This system is similar to the passive damper model when its parameters are allowed to vary. An active damper with direct feedback of the integral of measured force is represented by a model containing a single spring and a gain-dependent dashpot. Further aspects of the active damper are illustrated using a one-mode model of a vibrating structure. The effects of a feedforward modification to the system, and the analogy to changes in passive parameters, are illustrated by tracking the locus of the closed loop system poles with feedback gain.