Fault detection is a subfield of control engineering which concerns itself with monitoring a system, identifying when a fault has occurred and pinpointing the type of fault and its location. Two approaches can be distinguished: a direct pattern recognition of sensor readings that indicate a fault and an analysis of the discrepancy between the sensor readings and expected values. This book reviews research in the field of fault detection including the introduction of an automatic, effective but simpler-to-use system for fault diagnosis in bearings; the monitoring and diagnosis of discrete event systems using time petri nets; fault detection and diagnosis using statistical and soft computing methods.