A software license is a legal instrument (usually by way of

contract law A contract is a legally enforceable agreement between two or more parties that creates, defines, and governs mutual rights and obligations between them. A contract typically involves the transfer of goods, services, money, or a promise to tran ...

, with or without printed material) governing the use or redistribution of software. Under United States copyright law, all

software Software is a set of computer programs and associated documentation and data. This is in contrast to hardware, from which the system is built and which actually performs the work. At the lowest programming level, executable code consists ...

copyright A copyright is a type of intellectual property that gives its owner the exclusive right to copy, distribute, adapt, display, and perform a creative work, usually for a limited time. The creative work may be in a literary, artistic, education ...

protected, in both

source code In computing, source code, or simply 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 wo ...

and

object code In computing, object code or object module is the product of a compiler. In a general sense object code is a sequence of statements or instructions in a computer language, usually a machine code language (i.e., binary) or an intermediate langua ...

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 The public domain (PD) consists of all the creative work A creative work is a manifestation of creative effort including fine artwork (sculpture, paintings, drawing, sketching, performance art), dance, writing (literature), filmmaking, ...

, in which case it is also not covered by copyright and, as a result, cannot be licensed. A typical software license grants the

licensee A licensee can mean the holder of a license or, in U.S. tort law, a licensee is a person who is on the property of another, despite the fact that the property is not open to the general public, because the owner of the property has allowed the li ...

, typically an

end-user In product development, an end user (sometimes end-user) is a person who ultimately uses or is intended to ultimately use a product. The end user stands in contrast to users who support or maintain the product, such as sysops, system administrat ...

, permission to use one or more copies of software in ways where such a use would otherwise potentially constitute copyright infringement of the software owner's

exclusive rights In Anglo-Saxon law, an exclusive right, or exclusivity, is a de facto, non-tangible prerogative existing in law (that is, the power (sociology), power or, in a wider sense, right) to perform an action or acquire a benefit and to permit or deny ot ...

under copyright.

Software licenses and copyright law

Most distributed software can be categorized according to its license type (see table). Two common categories for software under copyright law, and therefore with licenses which grant the

specific rights, are

proprietary software Proprietary software is software that is deemed within the free and open-source software to be non-free because its creator, publisher, or other rightsholder or rightsholder partner exercises a legal monopoly afforded by modern copyright and int ...

and

free and open-source software Free and open-source software (FOSS) is a term used to refer to groups of software consisting of 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 ...

(FOSS). The distinct conceptual difference between the two is the granting of rights to modify and re-use a

software product Software is a set of computer programs and associated documentation and data. This is in contrast to hardware, from which the system is built and which actually performs the work. At the lowest programming level, executable code consists ...

obtained by a customer: FOSS software licenses both rights to the customer and therefore bundles the modifiable

with the software ("

open-source 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 sof ...

"), while proprietary software typically does not license these rights and therefore keeps the source code hidden ("

closed source Proprietary software is software that is deemed within the free and open-source software to be non-free because its creator, publisher, or other rightsholder or rightsholder partner exercises a legal monopoly afforded by modern copyright and inte ...

"). In addition to granting rights and imposing restrictions on the use of copyrighted software, software licenses typically contain provisions which allocate liability and responsibility between the parties entering into the license agreement. In enterprise and commercial software transactions, these terms often include limitations of liability, warranties and warranty disclaimers, and indemnity if the software infringes intellectual property rights of anyone. Unlicensed software outside the scope of copyright protection is either

public domain software Public-domain software is software that has been placed in the public domain, in other words, software for which there is absolutely no ownership such as copyright, trademark, or patent. Software in the public domain can be modified, distributed, ...

(PD) or software which is non-distributed, non-licensed and handled as internal business

trade secret Trade secrets are a type of intellectual property that includes formulas, practices, processes, designs, instruments, patterns, or compilations of information that have inherent economic value because they are not generally known or readily asc ...

. Contrary to popular belief, distributed unlicensed software (not in the public domain) is fully copyright protected, and therefore legally unusable (as no usage rights at all are granted by a license) until it passes into public domain after the

copyright term The copyright term is the length of time copyright subsists in a work before it passes into the public domain. In most of the world, this length of time is the life of the author plus either 50 or 70 years. Length of copyright Copyright subsists f ...

has expired. Examples of this are unauthorized

software leak An internet leak is the unauthorized release of information over the internet. Various types of information and data can be, and have been, "leaked" to the Internet, the most common being personal information, computer software and source code, a ...

s or software projects which are placed on public software repositories like

GitHub GitHub, Inc. () is an Internet hosting service for software development and version control using Git. It provides the distributed version control of Git plus access control, bug tracking, software feature requests, task management, continuous ...

without a specified license. As voluntarily handing software into the public domain (before reaching the copyright term) is problematic in some jurisdictions (for instance the

law of Germany The law of Germany (german: das Recht Deutschlands), that being the modern German legal system (german: Deutsches Rechtssystem), is a system of civil law which is founded on the principles laid out by the Basic Law for the Federal Republic of G ...

), there are also licenses granting PD-like rights, for instance the

CC0 A Creative Commons (CC) license is one of several public copyright licenses that enable the free distribution of an otherwise copyrighted "work".A "work" is any creative material made by a person. A painting, a graphic, a book, a song/lyric ...

WTFPL WTFPL is a permissive free software license. As a public domain like license, the WTFPL is essentially the same as dedication to the public domain. It allows redistribution and modification of the work under any terms. The title is an abbreviat ...

Ownership vs. licensing

Many

proprietary {{Short pages monitor