After the product prototype has been prepared, validation with the use of tests with users is carried out. The process starts with finding the right respondents and then recruiting them for research. The tests are carried out on the basis of written usability testing scenario, covering flow for individual personas. The next stage of validation is to conduct usability tests. For the results to be meaningful, at least five such tests should be carried out. Interestingly, the statistics show that such a number is sufficient to indicate key mistakes and design deficiencies. Validation ends with the preparation of the Usability Testing Report describing test results, along with user quotes and recordings from the process itself.