User Test / Testing
User testing is a step of the user-centered design in which the usability of wireframes, prototypes or final products is evaluated. Users from the target group are invited as test participants and perform typical tasks on the system. They are observed and interviewed by user experience professionals, who identify the weaknesses of the product and make suggestions for optimizing it. The most common method of user test / testing is the usability test.
Find a more detailed description of the method here: Usability Test