  In these lectures, which are written at an elementary and pedagogical level,
we discuss general aspects of (single) instantons in SU(N_c) Yang-Mills theory,
and then specialize to the case of N = 4 supersymmetry and the large N_c limit.
We show how to determine the measure of collective coordinates and compute
instanton corrections to certain correlation functions. We then relate this to
D-instantons in type IIB supergravity. By taking the D-instantons to live in an
$AdS_5\times S^5$ background, we perform explicit checks of the AdS/CFT
correspondence.
