  In this thesis, we investigate the implications of the LHC Higgs data on
different BSM scenarios. Since the data seem to agree with the SM expectations,
any nonstandard couplings will be strongly constrained. First we investigate,
in a model independent way, the constraints on the nonstandard Higgs couplings
with the fermions and the vector bosons in view of high energy unitarity and
the measured value of the Higgs to diphoton signal strength. Then we
concentrate on a particular BSM scenario, namely, the two Higgs-doublet models
(2HDMs). Consistency of the Higgs data with the corresponding SM predictions
strongly motivates us to work in the {\em alignment limit}. In this limit,
including the informations of Higgs mass and its SM-like nature, we find many
new constraints on the nonstandard masses and $\tan\beta$. We also study the
constraints on the charged scalar mass arising from the $h\to \gamma\gamma$
signal strength measurements and observe that the charged scalar does not
necessarily decouple from the diphoton decay width. We then move on to some
particular variants of 2HDMs, known as BGL models, and study the flavor
constraints on these models. Here we find that lighter than conventionally
allowed nonstandard scalars can successfully negotiate the stringent bounds
coming from flavor physics data and can leave unconventional decay signatures
that can be used as distinctive features of these models. We also analyze the
stability and unitarity constraints in a three Higgs-doublet model (3HDM) with
$S_3$ symmetry and find that there must be many more nonstandard particles
below 1~TeV. We also observe that the nondecoupling feature of the charged
scalar in the context of $h\to \gamma\gamma$ is not unique to the 2HDMs only,
instead it is a general property of the multi doublet extensions of the SM with
an exact discrete symmetry.
