Circumstellar matter studied with polarization

The study of starlight polarization provides insight into the physical mechanisms operating in and around the source as well 
as the source’s geometry. A particularly attractive feature of the technique is that the source does not have to be angularly 
resolved. This is often the case for stellar envelopes, which hence benefit from imaging and spectro-polarimetric observations. 
In this talk we will review mechanisms that polarize light in stellar envelopes and how the observations and modeling can be 
used to probe the circumstellar environment.