Part VII of NEC Art. 250 provides the requirements for equipment grounding. Because the Code often uses the word “grounding” to mean either grounding (a connection to the earth, see Art. 100 definition) or bonding (a metallic connection, see Art. 100 definition) it’s easy to become confused.
Equipment Grounding, Part 1
The goal is to prevent having two systems that are at different potentials from each other.