Web services and service oriented environments are key enablers for the migration of entertainment, business, sociability, science and health-care from the physical world to the virtual world. The result of this on-going migration is a new place very much different from the physical world, one where interconnected services interact with human users, sensors and embedded devices. Yet for this vision to become reality, trust needs to be addressed as members of the global e-society r- ularly today deal with the question whether they can trust other, unknown parties. Trust is a vital component of internet-based interactions and service-oriented en- ronment, but all too often it is assumed to be an implicit property that exists in the background rather than being an explicit property that is well-de ned and quant- able. While providing trust is challenging in existing computing systems, providing trust in service oriented environments is much more complex due to the dynamic and adaptable nature of these environment which are often large scale and across domains. To date the problem of trust for service oriented environments has been largely unexplored. This book represents the rst comprehensivecoverageof the principles,methods and systems for trust management and evaluation in service oriented environments.