All coordination methods follow some common principles, which are listed in the Coordination - general principles article.
A controller acting a ground position is responsible of any traffic movements on all aprons and taxiways. He ensures all ground security except on runways.
This position is present in many airfields and can be cumulated with TWR controller. This position may not exist in small airfields.
This coordination is not needed when DEL position is merged with GND position.
Any clearance that needs a runway crossing or taxiing must be coordinated with the TWR position. Any runways backtrack for a line up shall be handled by the TWR controller. Any taxiing on an active runway shall be handled by the TWR controller.
This coordination is not needed when TWR position is merged with GND position. Be aware that APP position is in charge of TWR position if this position is not opened.
In addition to the initial coordination, an aircraft could want to modify his departure clearance during taxiing.
This coordination is not needed when GND position is merged with APP position. Be aware that the en-route (CTR) controller is in charge of APP position if this position is not opened.