A subscription is required for this 9 page paper, published in May 2001 in the journal _Accounts of Chemical Research_ as part of a special issue on molecular machines. The URL links to the table of contents.

Abstract: Molecular motors convert chemical energy into mechanical force and movement. Operating at energies just above those of the thermal bath, these motors experience large fluctuations, and their physical description must be necessarily stochastic. Here, motor operation is described as a biased diffusion on a potential energy surface defined by the interactions of the motor with its track and its fuel. These ideas are illustrated with a model of the rotary movement of the motor.