True about Rest is:
Any component of a partial denture on a tooth surface, that provides vertical support is called rest.
Rests should always be located on properly prepared tooth surfaces. 
The prepared surface of an abutment to receive the rest is called the rest seat.
Rests are designated by the surface of the tooth, prepared to receive them (occlusal rest, lingual rest, and incisal rest).
Provides vertical support
Should always be located on properly prepared tooth surface
Rest are designated by the surface of the tooth prepared to receive them
All of the above