Blazars: Beamed or not Beamed

The author has proposed a picture where Blazars are active galactic nuclei consisting of jet structures, whose bulk velocity and beaming is increasing towards the outside. The X-ray optical and radio emission are produced at increasing distances from the center. This picture is suggested by a systematic study of the spectral shape at various frequencies and from the observation that in a number of objects the variability time scales are decreasing with frequency. The picture appears consistent with number counts for the class, without the requirement of special evolution of BL Lacs.