The concept of product defect and its synonyms used in the scientific literature are analyzed in the article. The types and causes of product defects are systematised on the basis of relevant regulatory documents. such as the Blue Guide to the Implementation of EU Product Rules and the World Health Organization Guide. as well as other legislation. https://www.roneverhart.com/Doorking-2334-080-VoIP-RS-232-Control-Box-for-1830-Series/