A typical distributed system consists of a collection of geographically dispersed autonomous processors which communicate among themselves exclusively by sending messages. In such systems, an effective management of distributed shared resources such as files and distributed objects is important. The design of an effective management depends critically on the design of distributed algorithms and the problem arising in the areas of telecommunications, distributed information processing, scientific computing and real time process control require efficient distributed algorithms. The objective here is how to design a preferred method to accomplish mutual exclusion for the shared resource by restricting its use to only one processor at a time. Due to the importance of shared resource allocation problem and its close association with mutual exclusion property in real time applications, the request based token control strategy for solving single shared resource allocation problem in distributed systems attracts more attention. This book deals with the single shared resource allocation, distributed sorting and prefix computation problems using token based message passing strategies.