Software for which the user pays no charge at all. It is a comparatively recent phenomenon. There are two reasons for individuals or companies developing such software: one is altruistic and the other is for commercial gain. The altruistic reason is that an individual may feel that there is a major demand for a particular program and that, as part of a community, he or she does not want to charge for it. Almost certainly the best example of this is the Linux operating system, a variant of UNIX, which can be run on a PC and which is maintained by a network of unpaid volunteers. The other reason for developing such software is for commercial gain: a company provides a version of a system or some core software, from which they can profit by offering services, selling computers, or selling add-on software. The best example of this is Java, much of which is available at no cost. See also Free Software Foundation.