The system oscillates/vibrates by itself after initial excitation

The system oscillates/vibrates continuously by external force

No energy losses during vibration

Energy losses occurs during vibration

- The system behave linearly
- The governing equations are linear

- At last one component behaves nonlinear
- The governing equations are nonlinear

- Motion can be described by a finite number of parameters (one angle needed to specify the position of a pendulum for example).
- System has a finite number of degrees of freedom.
- Also known as lumped-parameter systems.
- Typically modeled using ordinary differential equations.

- Requires an infinite number of parameters to describe the motion of the system (specifying the position of every point on a deformed beam for example).
- System has an infinite number of degrees of freedom.
- Also known as distributed systems.
- Typically modeled using partial differential equations.

The excitation on system can be determined at any given time

The excitation on system cannot be determined at any given time