The paper presents an overview of theories about the ISO 9001 standard, which emphasizes the audit of the standard. ISO 9001 has been found to be one of the most commonly used quality management standards today. The first ISO 9001 was published in 1987. It had a solid structure consisting of twenty requests. Although a positive shift in quality management has been achieved by default, ISO 9001 has generally described in detail what should be done, not how to do it. There was also the problem of unrelated important items within the text, ie the standard document. All this led to the need to revise the standards. An audit was carried out in 1994, which brought minor changes as the basic requirements of the standard remained unchanged, as did most of the current problems. Therefore, in 2000, a new audit was needed, which brought the biggest changes so far. There is a connection between the essential elements, as well as the principles that must be adhered to when managing quality according to ISO 9001: 2000. In 2008, another audit was published. This is a minor audit as most of the text has remained unchanged. The changes mainly relate to new and better clarifications of existing requirements. The last audit was performed in 2015. The requirements of the standards themselves have been expanded and new principles and concepts such as knowledge management, risk-based thinking and leadership have been introduced. This release has fixed some shortcomings, but there is still room for improvement, so a new audit can be expected in the near future. ISO conducts audits every five years, but it is clear from this paper that more time may pass until a new version of the standard. For this reason, organizations still need to focus on ISO 9001: 2015 when it comes to quality management based on norms and standards.