AbstractNowadays more effort has been spending on combining subsystems to form larger systems such as enterprise information management systems rather than simple database management systems. The security of the enterprise system emerges as a growing problem besides the difficulty of the creation of complex systems. One of the major adversities is the wideness of the system coverage area. Especially the concept of cloud computing introduced the notion of coverage without strict borders. The security of this notion also is a research topic. In this study, the security mechanisms and properties of web services as well as the usage areas are explained.