Description
Imaging Atmospheric Cherenkov Telescopes (IACT) are among the most sensitive instruments available to study the very high energy non-thermal sky, and the High Energy Stereoscopic System (HESS) is the largest such system operating in the world. This makes HESS an excellent tool for probing the extreme environment of Blazar jets. In this talk I will give a brief introduction to the principles behind IACT's, recent Blazar studies done by HESS, and report some preliminary results on very distant BL Lac.
