There are many ways to distribute software.
What distinguishes software distribution are the conditions under which a developer or corporation shares software with a user. Typically, the terms specify if and how the software can be copied, modified, redistributed, or commercialised. In most cases, these terms are wrapped in legal language in a document called a software licence.
Software licenses can be generally divided into following types, but for a deeper overview please refer Wikipedia.
A proprietary software license is a legal agreement between the owner of a piece of software (the licensor) and a user (the licensee) that governs the use, distribution, and modification of the software. In general, proprietary software licenses restrict the user's rights to use and modify the software, and often require the user to pay a fee to use the software. These licenses typically prohibit the user from copying or distributing the software without permission from the licensor, and may also limit the user's ability to reverse engineer or modify the software. Proprietary software licenses are different from open-source software licenses, which typically allow users to modify and distribute the software freely, as long as they abide by certain conditions, such as preserving the original copyright notices and licensing terms.
Freeware, shareware, and freemium are types of software licenses that offer different usage rights and payment models for software.
Freeware: Freeware is software that is available for free without any charge. Users can download, install, and use the software without paying any fees. Freeware software may or may not have certain limitations, such as limited features, advertising, or a request for donations. However, it is generally free to use and distribute.
Shareware: Shareware is software that is available for free, but with certain limitations or restrictions. Users can download and try the software for a limited period, after which they are required to purchase a license to continue using the software. Shareware software may have restricted features, time-limited usage, or a request for payment after a certain number of uses. The payment is usually a one-time fee, and the user receives the full version of the software.
Freemium: Freemium is a combination of "free" and "premium." Freemium software is available for free, but with certain features or functionality limited or locked. Users can upgrade to the premium version of the software by paying a fee, which unlocks additional features or functionality. Freemium software often offers a limited or basic version of the software for free, while more advanced features are only available in the paid version. This payment model is often used for mobile apps and online services.
A restrictive or copyleft open source license is a type of software license that imposes certain restrictions on the distribution and modification of the software. These licenses are designed to protect the rights of the software's creators and ensure that the software remains free and open. Under a restrictive open source license, anyone can use, modify, and distribute the software as long as they follow the conditions of the license. These conditions typically require that any modifications or derivative works be licensed under the same license, and that the source code of the software be made available to anyone who receives a copy. The most well-known restrictive open source licenses are the GNU General Public License (GPL) and the Affero General Public License (AGPL), which are widely used in the open source community. These licenses ensure that any software derived from the original work remains open source and that the code remains available to the public. Overall, the goal of a restrictive open source license is to encourage collaboration and ensure that the software remains open and accessible to everyone, while still protecting the rights of the original creators.
Copyleft is a legal concept that is used in open source software licensing to ensure that the software remains free and open. It is essentially the opposite of copyright, which is a legal mechanism that allows creators to restrict the use and distribution of their work.
Under copyleft, anyone can use, modify, and distribute the software as long as they follow the conditions of the license. These conditions typically require that any modifications or derivative works be licensed under the same license, and that the source code of the software be made available to anyone who receives a copy.
The goal of copyleft is to encourage collaboration and ensure that the software remains open and accessible to everyone, while still protecting the rights of the original creators. By requiring that any modifications or derivative works be licensed under the same license, copyleft ensures that the software remains open source and that the code remains available to the public.
A permissive open source license is a type of software license that grants users a wide range of freedoms to use, modify, and distribute the software with few or no restrictions. Unlike restrictive open source licenses, permissive licenses do not require that derivative works be licensed under the same license, and they do not typically require that the source code be made available to anyone who receives a copy. Permissive open source licenses are designed to be flexible and allow for the greatest possible reuse of the code. They are often used by commercial companies that want to incorporate open source code into their products without having to release their own code as open source. Examples of permissive open source licenses include the MIT License, the BSD License, and the Apache License. These licenses allow for a wide range of uses and modifications of the software, while still preserving some basic protections for the original creators, such as disclaimers of liability and copyright notices. Overall, the goal of permissive open source licenses is to encourage collaboration and innovation, while still providing some basic protections for the original creators. They offer a flexible and easy-to-use option for developers who want to share their code with the world while allowing for a wide range of uses and adaptations.
Public domain software is software that is not protected by copyright and is freely available for anyone to use, modify, and distribute without restriction. A public domain software license explicitly disclaims any copyright protection over the software, effectively placing it in the public domain. Public domain software is often used for software that is considered to be of little commercial value or for which copyright has expired. It can also be used for software that the creators want to share with the world without any restrictions or limitations. A public domain software license is not technically a license, as it does not impose any conditions or restrictions on the use or distribution of the software. Instead, it simply declares that the software is in the public domain and can be used and modified freely. However, it is important to note that the lack of copyright protection for public domain software means that there is no legal protection for the software or its creators. Anyone can use or modify the software in any way they choose, and there is no legal recourse for the original creators if their work is used inappropriately or without permission. Overall, the goal of a public domain software license is to make software available for anyone to use and modify without restriction, allowing for maximum collaboration and innovation. However, it is important to weigh the benefits of making software available in the public domain against the potential risks of losing control over the software and its use.