XGrid is a cluster computing technology developed by Apple Inc. and up until Mac Os 10.7 (Lion) It comes shipped and supported on every Mac. This default installation is what has helped XGrid become so popular, unfortuantely as of 10.8 (Mountain Lion) Apple have stopped supporting XGrid and is no longer in active development, but don't let that stop you (More to come on that soon)! XGrid is possibly one of the easiest grid technologies to set up, maintain and put to use within minutes. As said earlier, XGrid is available on all Macs prior to Mac OS 10.8 and only requires a Mac OS X Server to host the controller. Once the controller has been set up, there is a simple XML file that needs to be enabled on each node (Agent in XGrid terminology) and that is it. Once they have been enabled and the controller correctly and easily configured, then a user (client) can submit jobs to the grid via the GUI, command-line, third-party GUIs (GridStuffer is excellent) or via many of the API's available (Objective-C, Java and Python to name a few).