  In this work, we use two different methods to determine the opacity of the
TeV gamma-rays caused by the extragalactic background light (EBL) via e-e+
production due to photon-photon interaction. The first method, Model-Dependent
Approach, uses various EBL models for estimating the opacity as a function of
the redshift and energy of the TeV photons. The second method,
Model-Independent Approach, relies on using the simultaneous observations of
blazars in the MeV-GeV energy range from the Fermi-LAT and in the TeV band from
the ground-based gamma-ray telescopes. We make the underline assumption that
the extrapolation of the LAT spectrum of blazars to TeV energies is either a
good estimate or an upper limit for the intrinsic TeV spectrum of a source. We
apply this method on the simultaneous observations of a few blazars at
different redshifts to demonstrate a comparative study of six prominent EBL
models. Opacities of the TeV photons predicted by the model-independent
approach are systematically larger than the ones estimated from the
model-dependent method. Therefore, the gamma-ray observations of blazars can be
used to set a strict upper limit on the opacity of the Universe to the TeV
photons at a given redshift.
