ABSTRACT
Parallel and Distributed Computing has made it possible to simulate large infrastructures like Telecom networks, air traffic etcetera in an easy and effective way. This chapter discusses the problem of coordinating multiple computers and processors. First, it will look at distributed systems. These are interconnected groups of independent computers that need to communicate with each other to execute several jobs. Coordination is required to provide a service, share data, or even store data sets that are too large to fit on a single machine. A distributed system is a network of autonomous computers that communicate with each other in order to achieve a goal. The computers in a distributed system are independent and do not physically share memory or processors. Computers in a distributed system can have different roles. A computer's role depends on the goal of the system and the computer's own hardware and software properties.
