In the practical sub-module on the principles of personal data processing, examples of personal data processing are described during which one or more principles of personal data processing were violated. The aim of this practical module is to help entrepreneurs understand the principles outlined in Article 5 of the General Data Protection Regulation through specific practical examples. After reading the description of the situation in which a violation of the principles of personal data processing occurred, it is necessary to identify the exact principle or principles that were violated.