text: vations of VHE blazars, can measure both SED peaks 
  and are crucial for extracting information from the 
  observations of VHE blazars. They are used to con- 
  strain the size, magnetic ﬁeld and Doppler factor of 
  the emission region, as well as to determine the origin 
  (leptonic or hadronic) of the VHE γ-rays. In leptonic 
  scenarios, such MWL observations are used to mea- 
  sure the spectrum of high-energy electrons producing 
  the emission, as well as to elucidate the nature of the 
  seed photons. Additionally, an accurate measure of 
  the cosmological EBL density requires accurate mod- 
  eling of the blazar’s intrinsic VHE emission that can 
  only be performed with contemporaneous MWL ob- 
  servations. 