emissions are dominated by proton synchrotron emission, neutral pion decay photons, synchrotron and Compton emission from secondary decay products of charged pions.

Blazars are broadly classified in two groups namely BL Lacertae objects (BL Lacs) and Flat Spectrum Radio Quasars (FSRQs) [@Urry95]. BL Lacs are characterized by the weak or absence of thermal features like broad emission lines in their optical spectra. On the other hand, FSRQs exhibit luminous broad emission lines in their optical spectra. The peak frequency of the synchrotron component in the SED of blazars is usually used to subdivide them in 3-classes: low-synchrotron peaked (LSP: $\nu_{peak}<10^{14}$ Hz), intermediate-synchrotron peaked (ISP: $10^{14}$ Hz $<$ $\nu_{peak}$ $<$ $10^{15}$ Hz) and high-synchrotron peaked (HSP: $\nu_{peak}>10^{15}$ Hz) blazars [@Abdo10]. BL Lacs are assumed to be good VHE candidates for ground based TeV telescopes because their IC peak is in the TeV regime. To date, BL Lacs observed at VHE energies are predominantly high frequency peaked objects, which have been predicted as possible TeV candidate blazars [@Cost02].

Blazars often show violent flux variability from radio to VHE $\gamma$–rays at different time scales which may or may not be correlated. Therefore, simultaneous multi-wavelength (MWL) observations are important to understand the underlying physics 