Before you have a single real user in a testing session, you can already find a significant proportion of the usability problems in a design. Expert evaluation, also known as heuristic evaluation, is one of the most cost-effective methods available to UX practitioners. It requires no recruitment, facilities, or scheduling. What it does require is expertise, judgment, and a structured set of guidelines to work from.Here we show how expert evaluation works, walk through Nielsen’s widely used set of 10 heuristics, and explain how the same principles can be extended to benchmarking: a more formal process of scoring designs against detailed criteria and comparing performance across sites or over...