The question of how closely one can approach a well-known brand without infringing upon it is the subject of this investigation. At the center of this question is the concept of similarity of signs and its interpretation within the framework of the protective provisions of Section 14 (2) of the Trademark Act. The functions of the trademarks are crucial here. Ultimately, the exploitation of a brand's good reputation occurs in the mind of the consumer. Therefore, a separate chapter is dedicated to consumer psychology. The process of perception in the brain and its effects on the formation and transfer of brand images are explained, and from the insights gained, an approach to interpreting the concept of similarity of signs is developed.