The goal of heuristic evaluation is to find usability problems early in the design of a Web site so that improvements can be made as part of the iterative design process.

Heuristic evaluations usually are conducted by a small set (one to three) of evaluators. The evaluators independently examine a user interface and judge its compliance with a set of usability principles. The result of this analysis is a list of potential usability issues or problems. The usability principles, also referred to as usability heuristics, are taken from published lists. Ideally, each potential usability problem is assigned to one or more heuristics to help facilitate fixing the problem. As more evaluators are involved, more true problems are found.

Some evaluators try to estimate the degree to which each usability issue potentially could impede user performance or acceptance. This is done to help set priorities for making revisions to the system. However, judging the severity of proposed usability issues has been shown to be very difficult to do. More information: usability.gov/methods/heuristiceval.html