Four Freedoms (software) has part(s) freedom of usage
Free software or libre software is computer software distributed under terms that allow users to run the software for any purpose as well as to study, change, and distribute it and any adapted versions. Free software is a matter of liberty, not price; all users are legally free to do what they want with their copies of a free software (including profiting from them) regardless of how much is paid to obtain the program. Computer programs are deemed "free" if they give end-users (not just the developer) ultimate control over the software and, subsequently, over their devices.The right to study and modify a computer program entails that source code—the preferred format for making changes—be made available to users of that program. While this is often called "access to source code" or "public availability", the Free Software Foundation (FSF) recommends against thinking in those terms, because it might give the impression that users have an obligation (as opposed to a right) to give non-users a copy of the program.
Although the term "free software" had already been used loosely in the past and other permissive software like the Berkeley Software Distribution released in 1978 existed, Richard Stallman is credited with tying it to the sense under discussion and starting the free software movement in 1983, when he launched the GNU Project: a collaborative effort to create a freedom-respecting operating system, and to revive the spirit of cooperation once prevalent among hackers during the early days of computing.proprietary software, such as Microsoft Office, Windows, Adobe Photoshop, Facebook or iMessage from Apple. Users cannot study, change, and share their source code.
freeware or gratis software, which is a category of proprietary software that does not require payment for basic use.For software under the purview of copyright to be free, it must carry a software license whereby the author grants users the aforementioned rights. Software that is not covered by copyright law, such as software in the public domain, is free as long as the source code is in the public domain too, or otherwise available without restrictions.
Proprietary software uses restrictive software licences or EULAs and usually does not provide users with the source code. Users are thus legally or technically prevented from changing the software, and this results in reliance on the publisher to provide updates, help, and support. (See also vendor lock-in and abandonware). Users often may not reverse engineer, modify, or redistribute proprietary software. Beyond copyright law, contracts and lack of source code, there can exist additional obstacles keeping users from exercising freedom over a piece of software, such as software patents and digital rights management (more specifically, tivoization).Free software can be a for-profit, commercial activity or not. Some free software is developed by volunteer computer programmers while other is developed by corporations; or even by both.Definition and the Four Essential Freedoms of Free Software
The first formal definition of free software was published by FSF in February 1986. That definition, written by Richard Stallman, is still maintained today and states that software is free software if people who receive a copy of the software have the following four freedoms. The numbering begins with zero, not only as a spoof on the common usage of zero-based numbering in programming languages, but also because "Freedom 0" was not initially included in the list, but later added first in the list as it was considered very important.Freedom 0: The freedom to use the program for any purpose.
Freedom 1: The freedom to study how the program works, and change it to make it do what you wish.
Freedom 2: The freedom to redistribute and make copies so you can help your neighbor.
Freedom 3: The freedom to improve the program, and release your improvements (and modified versions in general) to the public, so that the whole community benefits.Freedoms 1 and 3 require source code to be available because studying and modifying software without its source code can range from highly impractical to nearly impossible.
Thus, free software means that computer users have the freedom to cooperate with whom they choose, and to control the software they use. To summarize this into a remark distinguishing libre (freedom) software from gratis (zero price) software, the Free Software Foundation says: "Free software is a matter of liberty, not price. To understand the concept, you should think of 'free' as in 'free speech', not as in 'free beer'". (See Gratis versus libre.)
In the late 1990s, other groups published their own definitions that describe an almost identical set of software. The most notable are Debian Free Software Guidelines published in 1997, and The Open Source Definition, published in 1998.
The BSD-based operating systems, such as FreeBSD, OpenBSD, and NetBSD, do not have their own formal definitions of free software. Users of these systems generally find the same set of software to be acceptable, but sometimes see copyleft as restrictive. They generally advocate permissive free software licenses, which allow others to use the software as they wish, without being legally forced to provide the source code. Their view is that this permissive approach is more free. The Kerberos, X11, and Apache software licenses are substantially similar in intent and implementation.
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