The study of close binary stars is of great importance in stellar astrophysics. The variability of the total light received from close binaries, provides the major source of information concerning stellar masses and dimensions. It conveys a substantial amount of geometrical, atmospheric and hydrodynamic information about these systems. The two major physical processes, other than obscuration of light during eclipses, that cause a variation of light and polarization with orbital phase are gravitational distortion and the reflection effect. The former phenomenon manifests itself through (i)...