The free software movement (abbreviated FSM) is a social movement which aims to promote user's rights to access and modify software. The alternative terms "software libre", "open source", and "FOSS" are associated with the free software movement. Although drawing on traditions and philosophies among members of the 1970s hacker culture, Richard Stallman is widely credited with launching the movement in 1983 by founding the GNU Project.
The free software philosophy at the core of the movement drew on core and incidental elements of what was called hacker culture by many computer users in the 1970s, among other sources.
Stallman founded the Free Software Foundation in 1985 to support the movement. The philosophy of the movement is to give freedom to computer users by replacing proprietary software under restrictive licensing terms with free software, with the ultimate goal of liberating everyone "in cyberspace" – that is, every computer user.
Members of the free software movement believe that all users of software should have the freedoms listed in the free software definition. Many hold that it is immoral to prohibit or prevent people from exercising these freedoms and that these freedoms are required to create a decent society where software users can help each other, and to have control over their computers.
Some adherents to the free software movement do not believe that proprietary software is strictly immoral. They argue freedom is valuable (both socially and pragmatically) as a property of software in its own right, separate from technical quality in a narrow sense.
The Free Software Foundation also believes all software needs free documentation (in particular because conscientious programmers should be able to update manuals to reflect modification that they made to the software), but deems the freedom to modify less important for other types of written works. Within the free software movement, the Floss manuals foundation specializes on the goal of providing such documentation. Members of the free software movement advocate that works which serve a practical purpose should also be free.
The initial work of the free software movement focused on software development.
The free software movement also rejects proprietary software, refusing to install software that does not give them the freedoms of free software. According to Stallman, "The only thing in the software field that is worse than an unauthorised copy of a proprietary program, is an authorised copy of the proprietary program because this does the same harm to its whole community of users, and in addition, usually the developer, the perpetrator of this evil, profits from it."
Some supporters of the free software movement take up public speaking, or host a stall at software-related conferences to raise awareness of software freedom. This is seen as important since people who receive free software, but who are not aware that it is free software, will later accept a non-free replacement or will add software which is not free software. 
A lot of lobbying work has been done against software patents and expansions of copyright law.
Congressmen Dr Edgar David Villanueva and Jacques Rodrich Ackerman have been instrumental in introducing in Republic of Peru bill 1609 on "Free Software in Public Administration". The incident immediately invited the attention of Microsoft Inc, Peru, whose General Manager wrote a letter to Dr Edgar David Villanueva. Dr Villanueva's response received worldwide attention and is still seen as a classical piece of argumentation favouring use of Free Software in Governments.
In the USA, there have been efforts to pass legislation at the state level encouraging use of free software by state government agencies.
Like many social movements, the free software movement has ongoing internal conflict between personalities and between supporters of compromise versus strict adherence to values.
In 1998, some companies met to create a marketing campaign for free software which would focus on technology rather than ethics. After this Eric Raymond and Bruce Perens, founded Open Source Initiative OSI, which promotes the term "open-source software" as an alternative term for free software. OSI does not agree with the free software movement's position that non-free software is a social problem or that it is unethical.
OSI advocates free software (under the name "open-source software") on the basis that it is a superior model for software development rather than it being a social or ethical issue. By 2005, Richard Glass considered the differences to be a "serious fracture" but "vitally important to those on both sides of the fracture" and "of little importance to anyone else studying the movement from a software engineering perspective" since they have had "little effect on the field".
Some free software advocates use the term Free and Open Source Software (FOSS) as an inclusive compromise, drawing on both philosophies to bring both free software advocates and open source software advocates together to work on projects with more cohesion. Some users believe that a compromise term encompassing both aspects is ideal, to promote both the user's freedom with the software and also to promote the perceived superiority of an open source development model.
The two most prominent people attached to the movement, Richard Stallman and Linus Torvalds, have deep philosophical differences. This has fueled many dramatic news articles, but has not prevented Stallman from using Torvalds' kernel or Torvalds from using Stallman's GNU General Public License and the GNU operating system.
Ohloh, a web service founded in 2004 and launched in 2006, monitors the development activity in the free software community, providing detailed metrics and quantitative analyses on the growth and popularity of projects and programming languages.
Some, such as Eric Raymond, criticise the speed at which the free software movement is progressing, suggesting that temporary compromises should be made for long-term gains. Raymond argues that this could raise awareness of the software and thus increase the free software movement's influence on relevant standards and legislation.
The free software movement is a software movement which aims to improve the user's rights on software and reducing proprietary (non-free) software through the use of operating systems such as Ubuntu. The movement is generally signified through open source software such as Mozilla Firefox, Mozilla Thunderbird, FileZilla and open source operating systems such as Linux and ReactOS. The movement is against non-free software that restricts the user's rights. Examples of non-free software include Microsoft Windows, Adobe Acrobat and UltraEdit.