A Mobile Agent (MA) is autonomous and identifiable software process that travel through a network of heterogeneous machine and act autonomously on behalf of user. Improving the survivability of MA in presence of various faults is the major issue concerns with implementation of MA. During its life cycle, a MA can fail due to some uncaught exception, failure of the MA executing platform/system, or its components or the host machine. The MA may also be lost on its way or blocked due to link failure. Since failure occurs at different places due to different reasons, specialized approaches should be used to tolerate different kinds of faults. Fault tolerance is defined as the ability of a system to withstand failure and continue to provide service in the event of an internal or external error. Fault tolerant systems are designed to ensure that in the event of a failure, crash, or a major user error, data is not lost and the system can continue to provide its specified services. This book explores the various issues and challenges related with designing of fault tolerant Mobile Agent Systems. It also discusses and compares various solutions for fault tolerant execution of Mobile Agents.