  We give a short introduction to Pade approximation (rational approximation to
a function with close contact at one point) and to Hermite-Pade approximation
(simultaneous rational approximation to several functions with close contact at
one point) and show how orthogonality plays a crucial role. We give some
insight into how logarithmic potential theory helps in describing the
asymptotic behavior and the convergence properties of Pade and Hermite-Pade
approximation.
