Free 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 regardless of how much is paid to obtain the program. Computer programs are deemed "free" if they give end-users ultimate control over the software and, subsequently, over their devices.
Freeware is software, most often proprietary, that is distributed at no monetary cost to the end user. There is no agreed-upon set of rights, license, or EULA that defines freeware unambiguously; every publisher defines its own rules for the freeware it offers. For instance, modification, redistribution by third parties, and reverse engineering are permitted by some publishers but prohibited by others. Unlike with free and open-source software, which are also often distributed free of charge, the source code for freeware is typically not made available. Freeware may be intended to benefit its producer by, for example, encouraging sales of a more capable version, as in the freemium and shareware business models.
In computing, source code is any collection of code, with or without comments, written using a human-readable programming language, usually as plain text. The source code of a program is specially designed to facilitate the work of computer programmers, who specify the actions to be performed by a computer mostly by writing source code. The source code is often transformed by an assembler or compiler into binary machine code that can be executed by the computer. The machine code might then be stored for execution at a later time. Alternatively, source code may be interpreted and thus immediately executed.
Open-source software (OSS) is computer software that is released under a license in which the copyright holder grants users the rights to use, study, change, and distribute the software and its source code to anyone and for any purpose. Open-source software may be developed in a collaborative public manner. Open-source software is a prominent example of open collaboration, meaning any capable user is able to participate online in development, making the number of possible contributors indefinite. The ability to examine the code facilitates public trust in the software.
In software engineering, a project fork happens when developers take a copy of source code from one software package and start independent development on it, creating a distinct and separate piece of software. The term often implies not merely a development branch, but also a split in the developer community; as such, it is a form of schism. Grounds for forking are varying user preferences and stagnated or discontinued development of the original software.
The first-sale doctrine is an American legal concept that limits the rights of an intellectual property owner to control resale of products embodying its intellectual property. The doctrine enables the distribution chain of copyrighted products, library lending, giving, video rentals and secondary markets for copyrighted works. In trademark law, this same doctrine enables reselling of trademarked products after the trademark holder puts the products on the market. In the case of patented products, the doctrine allows resale of patented products without any control from the patent holder. The first sale doctrine does not apply to patented processes, which are instead governed by the patent exhaustion doctrine.
Commercial software, or seldom payware, is a computer software that is produced for sale or that serves commercial purposes. Commercial software can be proprietary software or free and open-source software.
A software license is a legal instrument governing the use or redistribution of software. Under United States copyright law, all software is copyright protected, in both source code and object code forms, unless that software was developed by the United States Government, in which case it cannot be copyrighted. Authors of copyrighted software can donate their software to the public domain, in which case it is also not covered by copyright and, as a result, cannot be licensed.
Free and open-source software (FOSS) is software that is both free software and open-source software where anyone is freely licensed to use, copy, study, and change the software in any way, and the source code is openly shared so that people are encouraged to voluntarily improve the design of the software. This is in contrast to proprietary software, where the software is under restrictive copyright licensing and the source code is usually hidden from the users.
Free/open-source software – the source availability model used by free and open-source software (FOSS) – and closed source are two approaches to the distribution of software.
Multi-licensing is the practice of distributing software under two or more different sets of terms and conditions. This may mean multiple different software licenses or sets of licenses. Prefixes may be used to indicate the number of licenses used, e.g. dual-licensed for software licensed under two different licenses.
Commercial advantage of copyleft works differs from traditional commercial advantage of Intellectual Property Rights (IPR). The economic focus tends to be on monetizing other scarcities, complimentary goods rather than the free content itself. One way to make money with copylefted works is to sell consultancy and support for users of a copylefted work. Generally, financial profit is expected to be much lower in a "copyleft" business than in a business using proprietary works. Another way is to use the copylefted work as a commodity tool or component to provide a service or product. Android phones, for example, are based on the Linux kernel. Firms with proprietary products can make money by exclusive sales, by single and transferable ownership, and litigation rights over the work.
Companies whose business centers on the development of open-source software employ a variety of business models to solve the challenge of how to make money providing software that is by definition licensed free of charge. Each of these business strategies rests on the premise that users of open-source technologies are willing to purchase additional software features under proprietary licenses, or purchase other services or elements of value that complement the open-source software that is core to the business. This additional value can be, but not limited to, enterprise-grade features and up-time guarantees to satisfy business or compliance requirements, performance and efficiency gains by features not yet available in the open source version, legal protection, or professional support/training/consulting that are typical of proprietary software applications.
BSD licenses are a family of permissive free software licenses, imposing minimal restrictions on the use and distribution of covered software. This is in contrast to copyleft licenses, which have share-alike requirements. The original BSD license was used for its namesake, the Berkeley Software Distribution (BSD), a Unix-like operating system. The original version has since been revised, and its descendants are referred to as modified BSD licenses.
Proprietary software, also known as non-free software or closed-source software, is computer software for which the software's publisher or another person reserves some licensing rights to use, modify, share modifications, or share the software, restricting user freedom with the software they lease. It is the opposite of open-source or free software. Non-free software sometimes includes patent rights.
The GNU General Public License is a series of widely used free software licenses that guarantee end users the four freedoms to run, study, share, and modify the software. The license was the first copyleft for general use and were originally written by the founder of the Free Software Foundation (FSF), Richard Stallman, for the GNU Project. The license grant the recipients of a computer program the rights of the Free Software Definition. These GPL series are all copyleft licenses, which means that any derivative work must be distributed under the same or equivalent license terms. It is more restrictive than the Lesser General Public License and even further distinct from the more widely used permissive software licenses BSD, MIT, and Apache.
Software categories are groups of software. They allow software to be understood in terms of those categories, instead of the particularities of each package. Different classification schemes consider different aspects of software.
Open source is source code that is made freely available for possible modification and redistribution. Products include permission to use the source code, design documents, or content of the product. The open-source model is a decentralized software development model that encourages open collaboration. A main principle of open-source software development is peer production, with products such as source code, blueprints, and documentation freely available to the public. The open-source movement in software began as a response to the limitations of proprietary code. The model is used for projects such as in open-source appropriate technology, and open-source drug discovery.
Free and open source software (FOSS) is distributed under a variety of free-software licenses. These licenses differ significantly from other kinds of software licenses. Legal action against open source licenses involves questions about their validity and enforceability.
