we work on it for the standard family.

In this article we study few results on the boundaries of the Arnol’d tongues. We derive the first order asymtotic expansion of the boundary curves $\gamma_{p/q}^l$, $\gamma_{p/q}^r$ and $\gamma_{\alpha}$ near $a=0$. This gives the angle of opening for the boundaries of the rational tongues at $a=0$ and this Theorem \[prop\_angle\] is discussed in section \[sec\_angle\]. In the case of standard family the boundaries of the rational tongues $\cal T_{p/q}$ have the same tangency and the order of contact of these boundaries is obtained in section \[sec\_ooc\] using the technique of guided and admissible family. This is completely a new approach to prove the order of contact and this has further dynamical insight. The order of contact of the boundaries of the rational tongues in the standard family is connected with the parabolic multiplicity (see section 3 for definition) of the guiding family for the first time (see Theorem \[thm\_orderofcontact1st\]). In this way we obtain a result on the characterization of the admissible and guided family of analytic circle diffeomorphisms (see Theorem \[theo\_characteranalytic\]). We also prove that the boundaries of the rational tongue $\cal T_{p/q}$ are analytic curves in the parameter space for 