In its simplest case this sort of motion can be described with a sine function.
Coupled systems displaying this sort of behavior can exhibit normal modes, examples of which include symmetric and asymmetric stretching. This behavior is modeled with a second order homogeneous differential equation with a term corresponding to damping. This behavior occurs in RLC circuits analagously to a certain mechanical system with a dashpot. This sort of motion will typically occur in systems with a restoring force, such as systems which obey Hooke's law. In its simplest case this sort of motion can be described with a sine function. For 10 points, name this sort of behavior which occurs in the simple harmonic motion seen in a spring. 
Coupled systems displaying this sort of behavior can exhibit normal modes, examples of which include symmetric and asymmetric stretching.
oscillation [accept more specific answers; accept vibration; prompt on "simple harmonic motion" or "complex harmonic motion" or "damped harmonic motion" before mention of "simple harmonic motion"]