Stereotypes were introduced into the Unified Modeling Language (UML) to provide means of customizing this visual, general purpose, object-oriented modeling language, for its usage in specific application domains. The primary purpose of stereotypes is to brand an existing model element with a specific semantics. In addition, stereotypes can also be used as notational shorthand. The paper elaborates on this role of stereotypes from the perspective of UML, clarifies the role and describes a controlled experiment aimed at evaluation of the role - in the context of model understanding. The results of the experiment support the claim that stereotypes with graphical icons for their representation play a significant role in comprehension of models and show the size of the improvement.