Concurrent computing is a form of computing in which programs are designed as collections of interacting computational processes that may be executed in parallel.[1] Concurrent programs can be executed sequentially on a single processor by interleaving the execution steps of each computational process, or executed in parallel by assigning each computational process to one of a set of processors that may be close or distributed across a network. The main challenges in designing concurrent programs are ensuring the correct sequencing of the interactions or communications between different computational processes, and coordinating access to resources that are shared among processes.[1] A number of different methods can be used to implement concurrent programs, such as implementing each computational process as an operating system process, or implementing the computational processes as a set of threads within a single operating system process.