Heuristic evaluation is a usability engineering method for finding the usability problems in a user interface design so that they can be attended to as part of an iterative design process. These tests can be performed as paper prototypes or as electronic systems. This is because one person cannot find every problem in a system (only 35%), we must use multiple people because everyone uses it differently. Each participant performs the evaluation completely on their own to avoid bias. Findings from evaluations can either be personally written formal records, written by the evaluator afterwards, or notes can be taken by an observer, during the evaluation. Big difference of heuristic is that the observer is willing to answer questions from the evaluator, as well as provide hints for using the interface. It is better to split the tests up, into smaller tests focusing on specific aspects of the system.