Free Software is software distributed in a manner that grants users essential freedoms to run the program, study how it works, modify it and redistribute copies, including modified versions under the relevant licensing conditions. In this context, “free” refers primarily to freedom rather than price, a distinction traditionally expressed by the phrase “free as in freedom, not free as in price”. The Free Software Foundation describes these freedoms through four fundamental freedoms associated with running, studying, sharing and improving software. Access to the corresponding source code is necessary for meaningful study and modification. Free Software is therefore a philosophy and licensing concept concerned fundamentally with user rights and control over software.
The modern Free Software movement is strongly associated with Richard Stallman and the GNU Project, launched in 1983 with the objective of developing a complete Unix-like operating system composed of software respecting user freedoms. The Free Software Foundation was established in 1985 to promote these principles. The GNU General Public License became one of the most influential copyleft licences, using copyright law to impose conditions intended to preserve specified freedoms in redistributed versions.
The movement emerged partly in response to a computing environment in which software that had previously been shared and modified more freely was increasingly distributed under restrictive terms. Its historical importance extends beyond individual programs because it established a sustained legal and philosophical framework for software-user freedoms.
The four freedoms associated with Free Software are commonly numbered from zero through three. Freedom 0 concerns running the program for any purpose; Freedom 1 concerns studying how the program works and changing it, requiring access to source code; Freedom 2 concerns redistributing copies so others can benefit; and Freedom 3 concerns distributing modified versions so that improvements can benefit others. The numbering begins at zero because the framework was originally expressed in programming-oriented terms. These freedoms distinguish Free Software from freeware, where software may cost nothing but users do not necessarily receive source-code access or modification and redistribution rights.
Free Software licences implement these freedoms in legally enforceable terms. Some licences are permissive and allow incorporation into proprietary works under defined conditions, while copyleft licences require particular forms of reciprocity when covered software is redistributed. The GNU GPL is a prominent strong-copyleft licence, while the GNU Lesser General Public License provides a different framework commonly intended to permit certain forms of linking with software under other licences. The GNU Affero General Public License extends copyleft considerations to particular network-based software interactions. Licence compliance therefore requires understanding the exact licence and the circumstances of use, modification and distribution rather than applying a simplistic rule to every Free Software project.
Free Software has a philosophical dimension that distinguishes it from the more pragmatic framing traditionally associated with Open-Source Software. Both movements recognise a substantial overlapping body of licences and projects, and software meeting recognised open-source criteria will often also satisfy the practical freedoms associated with Free Software. However, the Free Software movement explicitly treats software freedom as an ethical and social issue concerning the relationship between users and technology. The Open Source movement historically placed greater emphasis on development methodology, practical advantages and business adoption. The overlap is substantial, but the terminology can communicate different priorities and values.
Free Software can be used commercially. The freedom to charge money for copies or services is compatible with the core concept, provided the licence freedoms are preserved. Businesses can sell physical media, provide support, offer consulting services, distribute packaged software or build commercial services around Free Software. A recipient who obtains a copy under an appropriate licence may still receive rights to study, modify and redistribute it. This means that the economic model and the freedom model are separate questions. A program can be commercially distributed while remaining Free Software, and a program can be provided at no charge while remaining non-free if users are denied the relevant freedoms.
Common misconceptions arise because everyday English uses “free” primarily to describe price. Free Software does not mean that every version must be gratis, that developers cannot earn money, that support must be free or that users can ignore licence obligations. Another misconception is that all software called “open source” must share precisely the same philosophical objectives as the Free Software movement. In practice, many projects are simultaneously described using both terms, while their communities may use the terminology differently. Correct classification depends on the actual licence and the rights it grants rather than on whether the download page says “free”, “open source” or “community edition”.
Free Software has had a major influence on software development, digital rights debates and the architecture of modern computing. GNU utilities, Linux distributions, programming tools, compilers, libraries, servers and development environments have contributed to a broad ecosystem in which users can inspect and modify substantial portions of their computing infrastructure. Its limitations can include the practical difficulty of maintaining complex software, ensuring adequate documentation, coordinating contributors and funding long-term development, particularly where projects rely heavily on volunteer labour. Its central significance, however, is the legal and ethical framework it establishes: software users are treated not merely as recipients of a finished product but as participants who should retain defined freedoms to use, study, share and improve the software.
