Earth - grounding is an object with an infinite number of free electrons.
What is grounding?
Grounding as a physical object is an object having an infinite number of free electrons.
Grounding is used to protect against electric shock to a person, to protect the device from interference, to protect the device itself from harmful radiation, to equalize the potentials of individual galvanically isolated units.
The ground is considered to be a conductor that is painted yellow.