Abstract: Trust is an important aspect of decision making for network-meditated principals, which can handle uncertainty,uncontrollabihty,fuzziness and incomplete information during interactions. Since trust management specifies,establishes,verifies and maintains trust relationships among principals, it receives increasing attention.On the basis of analyzing the existing concepts of trust and trust relationship, this paper presented the descriptive definition and the formal one of trust management, and discussed the relationship between them. Next, some typical trust management systems were introduced and compared. Based on the analysis of the shortcomings and problems of the existing trust. gement systems,we ended this paper with discussions on the trend of research and application.

Key words: Distributed systems, Trust management, Automated trust negotiation, Decision making