E-SPEAIT Week 6

 

When new programs or software is being released to public, developers put a copyright license on their work. Depending on their goals and intentions, the type of license may vary. The software may be for commercial use or non-commercial use and whether they plan to make money on it or just a contribution to the world. Copyleft license means that all downstream projects cant add other restrictions on the software. According to the Free Software Definition free software must fulfil 4 freedoms:

1.       The freedom to run the program, for any purpose.

2.       The freedom to study how the program works, and adapt it to your needs. Access to the source code is a precondition for this.

3.       The freedom to redistribute copies so you can help your neighbour.

4.       The freedom to improve the program, and release your improvements to the public, so that the hole community benefits. Access to the source code is a precondition for this.

Good example I found. If I wrote a program named MyProgram and started distributing it under a copyleft license, you would have the freedom to use and modify it. But when you give start distributing this with your changes, you have to give your users the same freedom I gave you.  Also, you don't have to use the same licenses I did, as long as the terms of licenses are compatible. But to make lives easier, usually the same license is being used.

Firstly there is strong copyleft. This essentially means that the first creator of the work has the most rights. This license can be imposed to all derived works. Thing to keep in mind is that if components with strong copyleft are used, the entire software has to be licensed under a compatible copyleft license.

Most popular example for strong copyleft license is the GNU General Public License (GPL). It has multiple versions and they have differences, so its necessary to concentrate and read them through to find the most suitable.

Secondly we have weak copyleft. This means that not all derived work gets the same copyleft license. Popular use for this is software libraries which allow links to other libraries. They allow free use and distribution. Weak copyleft license applies only to the original work.

Example for weak copyleft could be the GNU Lesser General Public License (LGPL).

Another option is no copyleft or public domain. This license would be used if the author doesn't want the ownership and they could just put their work in public domain. This allows people to do almost anything with the software and its source code.  Like selling, using, distributing and using for other software.

For public domain example we can bring out MIT X11 license, which allows multiple activities with the licensed code like petting different licenses on works derived from the code.

Overall choosing the best license really comes down your intentions. It requires a lot of reading and may be a headache, but thankfully there are helpful sites for picking.

 

Helpful site to help choosing a license according to your intentions: https://choosealicense.com/

Source for the good example: https://opensource.com/resources/what-is-copyleft

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