Unity Script Reference:
Legacy Documentation: Version 4.3.0
RigidbodyInterpolation
Description

Rigidbody interpolation mode.

For the main characters or vehicles that are followed by the camera it is recommended to use interpolation. For any other rigidbodies it is recommended not to use interpolation.

See Also: Rigidbody.interpolation variable.
Variables
None No Interpolation.
Interpolate Interpolation will always lag a little bit behind but can be smoother than extrapolation.
Extrapolate Extrapolation will predict the position of the rigidbody based on the current velocity.