  We discuss why the Slavnov higher covariant derivative regularization
appeared to be an excellent instrument for investigating quantum corrections in
supersymmetric gauge theories. For example, it allowed to demonstrate that the
$\beta$-function in these theories is given by integrals of double total
derivatives and to construct the NSVZ renormalization prescription in all
loops. It was also used for deriving the non-renormalization theorem for the
triple gauge-ghost vertices. With the help of this theorem the exact NSVZ
$\beta$-function was rewritten in a new form, which revealed its perturbative
origin. Moreover, in the case of using the higher covariant derivative
regularization it is possible to construct a method for obtaining the
$\beta$-function of ${\cal N}=1$ supersymmetric gauge theories, which
simplifies the calculations in a great extent. This method is illustrated by an
explicit two-loop calculation made in the general $\xi$-gauge.
