Wilson loops in large N field theories

We propose a method to calculate the expectation values of an operator similar to the Wilson loop in the large N limit of field theories. We consider N = 4 (3 + 1)-dimensional supersymmetric Yang-Mills theory. The prescription involves calculating the area of a fundamental string world sheet in certain supergravity backgrounds. We also consider the case of coincident M-theory five-branes where one is led to calculating the area of M-theory two-branes. We briefly discuss the computation for (2 + 1)-dimensional supersymmetric Yang-Mills theory with 16 supercharges which is nonconformal. In all of these cases, we calculate the energy of a quark-antiquark pair.