JINI IS MIDDLEWARE FOR building distributed systems in Java. It builds upon the distributed computing mechanisms of sockets and Remote Method Invocation. The intent is to offer "network plug and work," where new services can join a network of other services and be immediately useful, and where clients can search for and use these services. Jini has only been released for a little over a year as this is being written, and it introduces novel ideas and technologies for building distributed systems. This chapter gives a brief overview of the components of a Jini system and the relationships between them.