of $\cal N = $1 superconformal field theories \[64-65\] which contain adjoint matter fields. Also, one can introduce the confinement and broke the conformal symmetry by deforming the background further. This leads to chiral symmetry breaking and a running coupling constant \[20\].

-   Also, theories looking like $\cal N = $1 supersymmetric Yang-Mills theory in the IR can be obtained by considering higher dimensional D-branes wrapped on certain sub-manifolds of the ten dimensional geometry \[66-67\].

-   Deformations of the geometry lead to non-supersymmetric, non-conformal gauge theories which display confinement and chiral symmetry breaking \[18-19\]\[68-71\].

-   Fundamental matter can be added to the gauge theory by introducing D7-branes \[73\]. In the quenched approximation, $N_f \ll N_c$, their effect on the background geometry is ignored. Also, dynamical quarks can be added to this geometry \[73\].

-   Recently, some phenomenologically models have been suggested which are motivated by the AdS/CFT but not within the full string theory framework. These models are known as AdS/QCD \[74-77\].

-   Also, an approach similar to AdS/QCD is introduced based on the noncritical string theory in $d\ne 10$ dimensions \[42,77-78\].

Holographic QCD from the non-critical string theory 
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The key idea of construction of holographic models with flavors 