MPI stands for Message Passing Interface. As a software standard, it realizes the most important part of cluster intercommunication. It is the fundamental software layer upon which all program control and data communication is based. Although MPI defines a system with which the nodes of a cluster can communicate, it does not define the strict protocol with which this communication takes place. Despite this, every MPI implementation requires a standard application programming interface (API). In our case, MPI will make use of the TCP/IP protocol by sending data packets across the cluster's network backbone. The development of MPI began in 1992 and the following important key features, among others, were required:

These are included in the MPI 1.0 standard. Beginning with Version 2 of MPI, the following important features were added: