The process by which rocks are pulled apart. Commonly restricted to descriptions of the whole (continental) crust (e.g. the North Sea has formed by rifting). Note that rifting need not go to completion - opening up gaps in the crust. Essentially this is the opposite process to orogeny.
The splitting apart of continental masses. A rift is a long, narrow continental trough that is bounded by normal faults. It marks a zone along which the entire thickness of the lithosphere has ruptured under extension. The great continent Panagea was split apart by rifting.
The tearing apart of a plate to form a depression in the Earth's crust and often eventually separating the plate into two or more smaller plates.