free software, principle supporting the freedom of users to fully control their software. Software is considered “free” if it is offered by a developer without legal restriction against its study, redistribution, modification, or redistribution in modified form.
The promotion and propagation of free software is the chief aim of the free-software movement. The movement began in 1983, when programmer Richard Stallman announced his intention to create a free-software operating system named the GNU Project. Stallman went on to launch the Free Software Foundation (FSF) in 1985, an organization that remains a leading voice in the movement today.
According to the FSF, four essential freedoms must be available to a piece of software’s users for that software to be considered free software. Those freedoms are: (0) the freedom to run the software as desired and for any purpose, (1) the freedom to study or change the software, (2) the freedom to redistribute copies of the software, and (3) the freedom to distribute modified copies of the software. The numbering of these four freedoms begins with zero because “Freedom 0” was added to the list after the other three, but it is considered more foundational than the others.
There are implications to each of these four freedoms. To be exercised, for example, the first and third freedoms require that all free software be open source—that is, have the software’s source code accessible to users. Consequently, free software and open-source software are sometimes collectively referred to under the acronym FOSS, for free and open-source software. Some free software advocates object to this coupling, however, on the basis that the two terms are not necessarily synonymous; all free software is open source, but not all open-source software is free.
There are also notable exclusions from the FSF’s definition of free software. Perhaps counterintuitively, there is no requirement that free software be distributed without cost. On the contrary, free software advocates insist on its commercial viability. This for-profit use means that despite often being used interchangeably in common speech, “free software” and “freeware” are technically opposites: Free software may be offered at a price, so long as it is distributed without restrictions on its use, whereas freeware is defined by its lack of cost but not its restrictions.
In practice, free software has had mixed success in the for-profit world. Andrew Oram has written for the Linux Professional Institute that it is clear that “the accusation made by critics of free software over the past few decades—that you can’t build a business selling free software—is true.” However, many companies have successfully built their business models around the use of free software—e.g., the IBM subsidiary Red Hat, Inc. Moreover, free software is widely used by for-profit companies in non-customer-facing capacities, such as in their backend operations or the operating systems of their for-profit hardware. According to some studies, in fact, nine out of ten businesses may use free software in some capacity.
The best-known example of free software in commercial use is the free and open-source operating system Linux. Linux is currently the leading operation system for servers, mainframe computers, and supercomputers worldwide. The Linux “kernel” (core program) is also the basis for the best-selling smartphone operating system Android and the laptop operating system ChromeOS, arguably making it the most popular general operating system in the world.
Due to free-software developers’ efforts, free software now exists as an alternative to proprietary software for almost any functionality an individual user might desire, including e-mailing, word processing, graphics editing, Web surfing, and video calling. On the organizational level, free software is employed by organizations as different as Netflix, the U.S. Department of Defense, and the New York Stock Exchange. Studies agree that the resulting economic impact has been immensely positive, reducing the total cost of ownership and preventing vendor lock-in.
Perhaps as a result of this success, the free-software movement’s ideas and methods have been adopted by other industries and movements. Of particular note is the innovation of “copyleft,” a practice that uses copyright law to enshrine rather than restrict users’ freedoms. By placing free software under a license that requires any copy or modified form of the software to adhere to free-software principles, free-software developers prevent less altruistic users from modifying their software and then copyrighting the new version.