The term copyleft is used mostly in open source projects and has to do with software licensing which has created a certain uproar of discussions amongst text editors and authors of books. Before the concept of copyleft is introduced, we have to properly discuss the concept of copyright as copyleft is still under the same legal framework as copyright and they exist under the same rules. The exact concept of copyright differs amongst different jurisdictions but the overriding accepted concept is that it (copyright) attaches itself to a work done by an author. In a copyright agreement, no registration is required. This means the author can perform, modify and republish his work without permission anyone. The permission is a license that comes with a few terms and conditions that must be adhered to. Before we dive fully into the concept of copyleft, we first have to examine the meaning of “open source”. Open source license refers to licenses that allow for software and its information to be easily modified and shared. They also allow for easy access without permission for data on a open source to be used based on predefined terms and conditions.

Finally, to the definition of copyleft, it is referred to as the rule that when redistributing a program, you can’t deny other people the freedom of access to the software by adding more restrictions to the software. Copyleft is different from copyright in the sense that it offers people the right to distribute freely modified copies of a work within the stipulated same rights preserved in the original work. It is also referred to as protective or reciprocal, permissive free software license. Copyleft is a concept of licensing that maintains copyright conditions for projects ranging from art, documents, computer software and scientific discoveries. In copyleft, the author gives all the access of his rights under the copyright law although it allows him to impose few restrictions on activities, he considers to be exclusively reserved by him. The underlying concept under copyleft is that people benefit from the work of others, but modifications must be released publicly under some certain terms. Copyleft software, beyond individual creators, has a lot of economic effects and this has forced commercial producers to further increase the quality of their products which competes with free software.


Copyleft In Software Applications

A copyleft software or license refers to downstream projects which cannot add further restrictions on the use of the software. Let's use an example, if I wrote a pass exam once program, and I distributed it under a copyleft license, the public have free access to use and modify my program. But they can only work within the freedom of the restrictions I gave the program to allow external users. If I made the program under a permissive license, external users would be free to incorporate it under a closed software project that the open source gives access to.

Copyleft In Non-Software Applications

The notion of copyleft also exists out of the software world. Here, the idea is derived towards "do whatever you wish to do, along as you reserve the right for others to do equally the same thing as you". This is the distinguishing feature of the license been used for written work, and visual art. Generally, the use of copyleft in the non-software work is discouraged as it is not widely acceptable. Conclusively, when choosing a license for a project, you have to narrow the range of licenses that you believe match the objective and goals for the project. Also, take into consideration, the ecosystem in which your project will be based and the required technology required for it.


Copyleft In Software Applications

There are different types of copyleft licenses. There is the strong copyleft, and there is the weak copyleft. The strength of the copyleft is expressing the extent of restrictions provided for in the work of an author from which the license is derived.

Weak licenses are used in creating software libraries and they allow for other software’s to link up with the library. These licenses are redistributed without any legal restrictions under the library’s copyleft license. Only changes necessary for the weak-copylefted certificates are compiled and linked to the libraries. The most common free software license is the GNU also referred to as the General Public License. The strong copyleft license can also apply itself to any project, and not only documents the literature, music, video or photography, it also applies itself to contents on the open source.

There also exists full and partial copyleft issues. In the full copyleft, all parts of a project can be redistributed and modified under certain agreed terms and conditions. The partial copyrights on the other part, exempts parts of the project from copyleft restrictions and allowing users under the license not to impose any principle of copylefting on the work.

Another name for Copylefting is Viral Licensing. It is defined as any part of a work derived from copylefting must reserve the copyleft permissions when distributed.