A proprietary license can be discerned by the authorization of only few actions beyond the use of the program for the purpose for which it was intended.

A conventional clause to be found in commercial proprietary software licences is that the provided work is only licensed and not sold to the user which is often followed by the mantra in copyright law “all other rights reserved”. This set of provisions represents the “grant” clause which clarifies the scope of rights that are granted to the end user by the license agreement. The grant clause determines whether the license is exclusive or non-exclusive, the difference being that in the first case the use of the intellectual property right licensed is prohibited to everyone but the licensee.

Another type of clause, typical for commercial software, is the prohibition for the end user to distribute the software code. In this sense, the end user is permitted to install only one copy at a time on their device and is denied the possibility to make the software available on a network to be used by multiple devices or users.

Ordinarily, commercial software licenses would also contain a provision stating that the disassemble, reverse-engineer, decompile or any other attempts to derive or access the source code of the program would constitute a violation of the rights of the copyright holder or the licensor and would be subject to prosecution and damages.

Finally, a common clause is that the license agreement would be automatically (or upon a written notice by the licensor) terminated by the licensor in case the user fails to comply with any of the terms of the license agreement.

Proprietary licenses are subject to significant variation and can include clauses deviating from the aforesaid while at the same time preserving their overall proprietary nature. On the other hand, open source licenses provide for a more liberal approach, granting the licensee a considerably wider scope of rights.

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The GNU General Public License was written by Richard Stallman and is one of the most widely used copyleft software licenses, meaning it provides users with four basic freedoms:

oto use the software for any purpose,

oto change the software to suit his/her needs,

oto share the software, and

oto share the modifications made,

but at the same time relies on copyright to ensure that all derivative works are distributed under the same license terms, and the rewritten or redistributed software remains free software as in ensuring the four basic freedoms, listed above.

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Creative Commons (CC) licenses differ from conventional open-source licenses and are commonly used for design projects. A CC license has four basic elements, which can be included separately, cumulatively or in combinations with each other. The four elements include:

oAttribution. The author must be attributed as the creator of the work. Beyond that, the work can be copied, displayed, modified, distributed, and otherwise used.

oShare Alike. The work can be modified, distributed and so forth, but only under a license identical (“not more restrictive”) to the license that governs the original work. Without the share alike element derivatives of the work can be sublicensed under more restrictive CC licenses.

oNon-Commercial. The work can be modified, distributed and so on, but only for non-commercial purposes.

oNo Derivative Works. Licensees can copy, distribute, display and perform the licensed work in its original form only. Licensees can’t modify it in any way or create works based on the original.

Based on the permutations of those four elements six main CC licenses exist, varying from the most liberal – Attribution only (CC BY), to the most restrictive - Attribution-NonCommercial-NoDerivs (CC BY-NC-ND).

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The Mozilla Public License (MPL) is another open source/free software license, created and maintained by the Mozzila Foundation. The MPL establishes a middle ground between the GNU GPL (copyleft) and the permissive free software (BSD) licenses since it seeks to find a balance between the interests of proprietary and open source code developers. While the so called by the MPL “Covered Code” is subject to many of the restrictions present in the copyleft licenses such as the requirement that it should be made available in open source form, the MPL also permits that such “Covered Code” could be used in larger works meaning that MPL-licensed code can be combined with code licensed under another license. The latter is the main difference between the GPL (which prohibits such conduct) and the BSD License (which permits it).