Vibration is a mechanical phenomenon whereby oscillations occur about an equilibrium point. The word comes from Latin vibrationem ("shaking, brandishing").

Vibration Analysis (VA), applied in an industrial or maintenance environment aims to reduce maintenance costs and equipment downtime by detecting equipment faults.

In terms of mechanical vibrations for machine diagnosis, the vibration analysis is a very important technique. It is based on the high information content provided by the machine vibration signals that are an indicator of machine condition, used for the diagnosis of faults. Vibration analysis is fundamental in a predictive maintenance programme, being widely used for detection and monitoring incipient and severe faults in machinery parts, like bearings, shafts, couplings, rotors, motors etc. Some problems that are usually detected by vibration analysis are: unbalance, misalignment, bent shaft, rolling bearing faults, eccentricity, resonance, looseness, rotor rub, fluid-film bearing instabilities, gear faults, belt/sheave problems.