EPICS (Experimental Physics and Industrial Control System) is a toolchain allowing the user to create a professional control system infrastructure. EPICS is developed by the Argonne National Laboratory located in Lemont, Illinois, USA, the Berliner Elektronenspeicherring-Gesellschaft für Synchrotonstrahlung mbH (BESSY) from Germany and others.
It is licensed as open source software under the EPICS Open License (http://aps.anl.gov/epics/license/open.php) which is very similar to the BSD license but contains some additional privileges for the US government funding the work on the project.
Please note that EPICS is not a control system by itself but a tool to create one. Therefore, the user has to create a so called "input/output controller" (IOC) by using the scripts and Makefiles ("EPICS Build") provided in this EPICS base package.