it is reasonable to expect that some of the techniques used in road traffic theory would apply to modeling of traffic on the world wide web. we review the derivation and use of entropy maximizing models for the traffic distribution problem, which calls for the solution of a matrix balancing problem, and then apply a similar approach to estimating traffic on the www, which results in a hybrid matrix balancing model. recent work has shown that a more general non-linear interior-point optimization algorithm is also surprisingly efficient for these very large-scale problems.