Grounding is the process of connecting something to the earth. This is typically accomplished through the grounding electrode system.

An equipment grounding conductor (EGC) connects the non-current carrying metal parts of equipment and metal enclosures to the grounded conductor at the service or separately derived system, which in turn is connected to the grounding electrode system, thus providing a low impedance path to carry fault current in the event of a fault to ground occurring in an electrical system circuit.

Bonding is the process of joining metal enclosures, equipment, raceways, metal water piping, gas piping, structural steel, and the like together. Bonding items together and connecting the bonded items to an equipment grounding conductor places everything at the same potential and ensures an effective ground-fault current path in the event of a fault to ground occurring in an electrical system circuit.

Sometimes the same wire can serve both as an equipment grounding conductor and as an equipment bonding jumper.

Below are a few of the NEC^® Article 100 definitions pertaining to bonding and grounding:

Below is a preview of the NEC^®. See the actual NEC^® text at NFPA.ORG for the complete code section. Once there, click on their link to free access to the 2020 NEC^® edition of NFPA 70.

2020 Code Language:

Article 100:

Bonded (Bonding). Connected to establish electrical continuity and conductivity.

Bonding Conductor or Jumper. A reliable conductor to ensure the required electrical conductivity between metal parts required to be electrically connected.

Bonding Jumper, Equipment. The connection between two or more portions of the equipment grounding conductor.

Bonding Jumper, Main. The connection between the grounded circuit conductor and the equipment grounding conductor, or the supply-side bonding jumper, or both, at the service.

Ground. The earth.

Grounded (Grounding). Connected (connecting) to ground or to a conductive body that extends the ground connection.

Grounded, Solidly. Connected to ground without inserting any resistor or impedance device.