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A fully automatic system that can identify internal defects and forecast their remaining usable life is needed for smart factories worldwide. Utilizing the “predictive maintenance” method is one way to do this. It allows for intervention before failure occurs and considerably raises the efficiency of engineering components. Condition monitoring of rotating machinery can be done by vibration analyses utilizing various characteristic frequencies. Common defects like shaft misalignment, unbalanced, bend shafts, bearing defects and gear defects in rotating machinery must be identified before failure occurs. With the aid of frequency analysis, these errors can be anticipated. This paper covers a brief review of different fault diagnosis techniques, vibration analysis for fault detection and diagnosis, signal processing techniques, sensor position, dominant frequencies and the vibrational plane of different faults in rotating machinery.