Open Source licenses fall under two categories- those that aim to retain the freedom of the software itself (a copyleft license) and those that aim to give freedom to the users of that software (permissive license).

An example of a copyleft free software license is the GNU General Public License (GPL). This license is aimed at giving the end-user significant permission, such as permission to redistribute, reverse engineer, or otherwise modify the software. These permissions are not entirely free of obligations for the end-user, however. The end-user must comply with certain terms if the end-user wishes to exercise these extra permissions granted by the GPL. For instance, any modifications made and redistributed by the end-user must include the source code for these, and the end-user is not allowed to re-assert the removed copyright restrictions back over their derivative work. The GNU General Public License is often called the GNU GPL for short; it is used by most GNU programs, and by more than half of all free software packages. The latest version is version 3.

An example of the permissive free software license is the BSD License, which grants the user with the permission to do anything they wish with the source code, including the right to take the code and use it as part of a commercial software venture.

GNU License Types

The GNU Project was launched in 1984 to develop a complete Unix-like operating system which is free software – the GNU system.

Free software is a matter of the users’ freedom to run, copy, distribute, study, change and improve the software.

GNU has a number of licenses all geared towards different uses of software. They are:

The GNU General Public License, which is often called the GNU GPL for short; it is used by most GNU programs, and by more than half of all free software packages. The latest version is version 3.

The GNU Lesser General Public License, which is used by a few (not by any means all) GNU libraries. The latest version is version 3.

The GNU Affero General Public License, is based on the GNU GPL, but has an additional term to allow users who interact with the licensed software over a network to receive the source for that programme. The latest version is version 3.

The GNU Free Documentation License, is a form of copyleft intended for use on a manual, textbook or other document to assure everyone the effective freedom to copy and redistribute it, with or without modifications, either commercially or non-commercially. The latest version is 1.3.

Creative Commons License Types

Creative Commons is a non-profit corporation dedicated to making it easier for people to share and build upon the work of others, consistent with the rules of copyright.

The following describes each of the six main licenses offered when publishing work with a Creative Commons license.

Attribution Non-commercial No Derivatives (by-nc-nd) – This license is the most restrictive of the Creative Commons licenses, allowing redistribution. This license is often called the ‘free advertising’ license because it allows others to download a product or work and share them with others as long as the user mentions the original source and links back to the original source in some way. None of the work or product may be changed or used commercially.

Attribution Non-commercial Share Alike (by-nc-sa) - This license lets users play with a product and build upon it in a non-commercial way, as long as the source is credited and new creations or products are licensed under the same terms. Hence, nothing derived from this original product can be commercial in nature.

Attribution Non-commercial (by-nc) – This license lets users play with a product and build upon it in a non-commercial way, as long as the source is credited and new creations or products do not have to be licensed under the same terms.

Attribution No Derivatives (by-nd) – This license allows for

redistribution, commercial and non-commercial use, as long as it is passed along unchanged and in whole, with source fully credited.

Attribution Share Alike (by-sa) – This license lets users play with a product and build upon it in a commercial way, as long as the source is credited and new creations or products are licensed under the same terms. This license is often compared to open source software licenses.

Attribution (by) – This license lets users play with a product, build upon in a commercial way, as long as the source is credited as creator of the original work.

Choosing a license for your software programme which best suits your software programme, work or creation can be a difficult process but keeping the ultimate purpose of your work in mind at all times will aid your decision.

Click here to read about Propriety & Free Software Licenses.