This document discusses inductive proximity sensors. It defines inductive proximity sensors as electronic devices that can detect metal objects without physical contact through the use of magnetic fields. It explains that inductive proximity sensors work by inducing eddy currents in nearby metal objects using a magnetic field, which are then detected. The document notes there are differences between shielded and non-shielded inductive sensors and provides examples of inductive sensor applications like position determination, camshaft interrogation, and use in wind power plants.