When talking about service descriptions at least three important aspects have to be considered: functional, behavior and non-functional aspects. Although functional and behavior aspects are represent in many approaches the core of service description, non-functional aspects have nevertheless an important role expecely when we think about aspects like: security, service level agrement, etc. The aim of this project is to survey existing approaches for describing non-functional aspects of of systems and to determine which characteristics are more important when modeling non-functional properties.