A Wellbore is any hole drilled for the purpose of exploration for or extraction of natural resources such as water, gas or oil where a well may be produced and a resource is extracted for a protracted period of time.

It is often used interchangeably with borehole though typically a borehole is referred to in ore mining exploratory drilling or pilot holes for installing piers or underground utilities or any other of a number of single use hole drilling.

See Drilling rig (petroleum) for a diagram of a drilling rig.