  We review modifications of the Bekenstein-Hawking area law for black hole
entropy in the presence of higher-derivative interactions. In four-dimensional
N=2 compactifications of string theory or M-theory these modifications are
crucial for finding agreement between the macroscopic entropy obtained from
supergravity and the microscopic entropy obtained by counting states in string
or M-theory. Our discussion is based on the effective Wilsonian action, which
in the context of N=2 supersymmetric theories is defined in terms of
holomorphic quantities. At the end we briefly indicate how to incorporate
non-holomorphic corrections.
