Software license in the context of Clickwrap

Open-source licenses are software licenses that allow content to be used, modified, and shared. They facilitate free and open-source software (FOSS) development. Intellectual property (IP) laws restrict the modification and sharing of creative works. Free and open-source licenses use these existing legal structures for an inverse purpose. They grant the recipient the rights to use the software, examine the source code, modify it, and distribute the modifications. These criteria are outlined in the Open Source Definition.

After 1980, the United States began to treat software as a literary work covered by copyright law. Richard Stallman founded the free software movement in response to the rise of proprietary software. The term "open source" was used by the Open Source Initiative (OSI), founded by free-software developers Bruce Perens and Eric S. Raymond. "Open source" emphasizes the strengths of the open development model rather than software freedoms. While the goals behind the terms are different, open-source licenses and free-software licenses describe the same type of licenses.

A free-software license is a notice that grants the recipient of a piece of software extensive rights to modify and redistribute that software. These actions are usually prohibited by copyright law, but the rights-holder (usually the author) of a piece of software can remove these restrictions by accompanying the software with a software license which grants the recipient these rights. Software using such a license is free software (or free and open-source software) as conferred by the copyright holder. Free-software licenses are applied to software in source code and also binary object-code form, as the copyright law recognizes both forms.

Free and open-source software (FOSS) is software available under a license that gives users the right to use, share, modify, and distribute the software – modified or not – to everyone and provides the means to exercise those rights using the software's source code. FOSS is an inclusive umbrella term encompassing free software and open-source software. The rights guaranteed by FOSS originate from the "Four Essential Freedoms" of The Free Software Definition and the criteria of The Open Source Definition. All FOSS can have publicly available source code, but not all source-available software is FOSS. FOSS is the opposite of proprietary software, which is licensed restrictively or has undisclosed source code.

The historical precursor to FOSS was the hobbyist and academic public domain software ecosystem of the 1960s to 1980s. Free and open-source operating systems such as Linux distributions and descendants of BSD are widely used, powering millions of servers, desktops, smartphones, and other devices. Free-software licenses and open-source licenses have been adopted by many software packages. Reasons for using FOSS include decreased software costs, increased security against malware, stability, privacy, opportunities for educational usage, and giving users more control over their own hardware.

An open file format is a file format for storing digital data, defined by an openly published specification usually maintained by a standards organization, and which can be used and implemented by anyone. An open file format is licensed with an open license.For example, an open format can be implemented by both proprietary and free and open-source software, using the typical software licenses used by each. In contrast to open file formats, closed file formats are considered trade secrets.

Depending on the definition, the specification of an open format may require a fee to access or, very rarely, contain other restrictions. The range of meanings is similar to that of the term open standard.

Pre-installed software (also known as bundled software) is software already installed and licensed on a computer or smartphone bought from an original equipment manufacturer (OEM). The operating system is usually factory-installed, but because it is a general requirement, this term is used for additional software apart from the bare necessary amount, usually from other sources (or the operating system vendor).

Unwanted factory-installed software (also known as crapware or bloatware) can include major security vulnerabilities, like Superfish, which installs a root certificate to inject advertising into encrypted Google search pages, but leaves computers vulnerable to serious cyberattacks that breach the security used in banking and finance websites.

An app store, also called an app marketplace or app catalog, is a type of digital distribution platform for computer software called applications, often in a mobile context. Apps provide a specific set of functions which, by definition, do not include the running of the computer itself. Complex software developed for personal computers may have a corresponding mobile app optimized for the device’s constraints. Today apps are normally designed to run on a specific mobile operating system—such as the contemporary iOS, iPadOS, Windows Phone, or Android—but in the past mobile carriers had their own portals for apps and related media content.

An app store can be thought as a restricted, commercial version of a package manager, although an app store provides additional services like app discovery, user reviews, security screening, licensing enforcement, and seamless integration of a payment system. Unlike traditional package managers, which prioritize dependency management and system integration, app stores focus on usability, monetization, and a curated user experience.

Freeware is software, 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; or by collecting and selling user's personal data.

The LaTeX Project Public License (LPPL) is a software license originally written for the LaTeX system. Software distributed under the terms of the LPPL can be regarded as free software; however, it is not copylefted.

Besides the LaTeX base system, the LPPL is also used for most third-party LaTeX packages. Software projects other than LaTeX rarely use it.

Copyleft is the legal technique of granting certain freedoms over copies of copyrighted works with the requirement that the same rights be preserved in derivative works. In this sense, freedoms refers to the use of the work for any purpose, and the ability to modify, copy, share, and redistribute the work, with or without a fee. Licenses which implement copyleft can be used to maintain copyright conditions for works ranging from computer software, to documents, art, and scientific discoveries, and similar approaches have even been applied to certain patents.

Copyleft software licenses are considered protective or reciprocal (in contrast with permissive free software licenses): they require that information necessary for reproducing and modifying the work be made available to recipients of the software program. This information is most commonly in the form of source code files, which usually contain a copy of the license terms and acknowledge the authors of the code. Copyleft helps ensure everyone's rights to freely use the product but it prohibits owning, registering copyright and earning royalties from copyright.

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, or sold even without any attribution by anyone; this is unlike the common case of software under exclusive copyright, where licenses grant limited usage rights.

Under the Berne Convention, which most countries have signed, an author automatically obtains the exclusive copyright to anything they have written, and local law may similarly grant copyright, patent, or trademark rights by default. The Convention also covers programs, and they are therefore automatically subject to copyright. If a program is to be placed in the public domain, the author must explicitly disclaim the copyright and other rights on it in some way, e.g. by a waiver statement. In some jurisdictions, some rights (in particular moral rights) cannot be disclaimed: for instance, civil tradition-based German law's "Urheberrecht" differs from Anglo-Saxon common law tradition's "copyright" concept.

Software relicensing is applied in open-source software development when software licenses of software modules are incompatible and are required to be compatible for a greater combined work. Licenses applied to software as copyrightable works, in source code as binary form, can contain contradictory clauses. These requirements can make it impossible to combine source code or content of several software works to create a new combined one.

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.

When software is multi-licensed, recipients can typically choose the terms under which they want to use or distribute the software, but the simple presence of multiple licenses in a software package or library does not necessarily indicate that the recipient can freely choose one or the other. In some cases, especially when the software has multiple origins, all the accompanied licenses apply at the same time. The applicability of the different licenses has to be individually checked. The distributor may or may not apply a fee to either option. The two usual motivations for multi-licensing are license compatibility and market segregation based business models.