Literally, grounding and earthing mean making a connection with ground and earth, respectively. To save copper the planet Earth was used as return path for the telegraph signals and grounding became a synonym for return path. This chapter discusses grounding in low-voltage power distribution networks, lightning protection and ground as signal return. The system grounding in low-voltage power distribution grid is designed for the safety of persons, livestock, and property and not necessarily for electromagnetic compatibility (EMC). The most common types of grounding systems are TT, TN, and IT. Also medical treatment areas typically employ a star-shaped grounding system, because already a very small, low frequency, leakage current through a patient may cause significant harm or even death. Bonding all grounding conductors together reduces the risk of resonances and flash-overs at the cost of the occurrence of a disturbance voltage in the differential mode (DM) circuit caused by currents in the common mode (CM) circuit.