Normally open contact In the normal state (without power), the contact in the open state is called the normally open contact.
Normally closed contact In the normal state (no electricity, no current flow), the contact in the closed state is called the normally closed contact.
Normally open-NO (normal open) is usually a circuit disconnected state, that is, the coil is disconnected when there is no power. Normally closed-NC (normal close) is usually the circuit closed state, that is, the coil is closed when there is no electricity.