Dual Licensing

   
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Software Licenses   >   Glossary   >   Dual Licensing

   
 

Dual Licensing


Dual Licensing is the practice of distributing a particular piece of software under more than once license agreement, giving recipient's a choice of which agreement they wish to license the software under. In some cases a copyright-holder or distributor may offer a choice of more than two licenses, and this is usually described as "tri-licensing" or "multi-licensing".

Perhaps the most common form of dual licensing is when a software vendor offers their software under both an open-source copyleft license, and a proprietary license. This allows licensees wanting to prepare derivative works a choice of distributing such works also under a copyleft license, or paying a fee if they wish to distribute their derivative works under a proprietary license. Examples of software which use dual licensing of this type, include Qt by TrollTech, and MySQL.

Another reason why software may be dual licensed, is because of license compatibility issues. For example, if a copyright-holders wants to make his software available to a wide range of Open-Source projects, he may dual license (or multi-license) his software, allowing many different projects to use, modify and distribute it.

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