A shaft coupling is a mechanical component that connects the drive shaft and driven shaft of a motor, pump etc., to transmit power. Shaft couplings introduce mechanical flexibility, providing tolerance for shaft misalignment. As a result, this coupling flexibility can reduce uneven wear on the bearing, equipment vibration, and other mechanical troubles due to misalignment. Shaft couplings serve as an important link to minimize impact and vibration, allowing smooth rotation to be transmitted. This module covers the concept of coupling, its usages and introduction to various rigid and flexible couplings used in industries.