I give an overview on recent advances in our understanding of the blazar phenomenon.
I focus in particular on results provided by the new generation of large-area GeV and TeV telescopes, which have revealed several new aspects of blazars' structure and emission properties. On the one hand, the blazar-sequence scenario seems confirmed in its main features, although with differences between FSRQ and BL Lacs. Yet it remains uncertain if it is real or caused by selection biases. On the other hand, several other results are challenging the standard emission models, like the absence of the cut-off in the gamma-ray spectrum expected if produced inside the Broad Line Region, the existence of extreme-TeV BL Lacs with gamma-ray emission peaking at multi-TeV energies, and ultrafast variability on scales much less than the size of the black hole. This review does not aim to be exhaustive nor complete, but to provide an update on some main topics from observational results emerged in the last years.