The Spectral Sequence of Blazars - Status and Perspectives

The present status of the blazar spectral sequence is discussed, including new findings about blazars selected with different criteria than the original complete radio-samples. Despite extensive searches of blazars "breaking" the sequence, the original idea proposed 10 years ago, still seems to hold. On the other hand the forthcoming launch of the GLAST satellite will provide a new selection band for blazars and blazar related populations as well as fantastic progress on the spectra and variability behaviour of presently known blazars. The order of magnitude increase in sensitivity of GLAST will allow to detect gamma-rays from jets with lower power and/or lower beaming factor, thus sampling a much wider population.