Grid Computing has become a separate research field in the '90s and since then it has been targeted by many projects all around the world. Several years ago users and companies having computation and data intensive applications looked sceptical at the forerunners of Grid solutions that promised less execution time and easy-to-use application development environments by creating a new virtually unified high performance system of interconnected computers from all around the world. Resource management in Grid systems is the research field most affected by user demands. Though well-designed, evaluated and widely used resource managers (also called as brokers) have been developed, new capabilities are required, such as interoperability and agreement support. This book aims at providing high-level brokering solutions to establish Grid Interoperability, which means the bridging of different Grid infrastructures in order to allow users on one Grid to run computing jobs and exchange data with users on other Grids.