This thesis is focused on analyzing the current state of SaaS (Software as a Service) and impact of SaaS on corporate's ICT as a whole. The aim is to explain the concepts and implications of modern forms of providing services, to describe and to evaluate their benefits and risks and to assess future developments in this area. The attention will be paid on specifics of the environment of Czech companies. The first part of this work deals with the current SaaS solutions and related technologies. Emphasis is placed on acquainting the reader with currently available (or introduced by mid-2011) technologies and their mutual relationships. This section also summarizes the current level of knowledge of the field and on this basis provides definiti...