We live in a digital world and constantly consume or create data. Under the hood there is software which makes it possible for the data to be created or consumed. This software, in other words, apps, tools, programs etc are the creation of and by people over a period of time (generally it takes years for a piece of software like Operating system to evolve). In this process developers and users of the software get into an agreement which governs the use, modification and redistribution of the software also called license agreement.
When it comes to Free Software licenses the users and developers have the freedom to do what they wish to do in contrast proprietary licenses restrict users/developers are are told what they can not do.
Other than these two variants of licenses there is a third category of licenses called Open Source licenses. OSS (Open Source Software) claims that their licenses are more open and less restrictive than FS (Free Software) licenses, But the reality is that these licenses are created in such a way that the parts of software created with these licenses can be closed giving a huge advantage and control to the giant corporations which mix OSS with propitiatory software. OSS licenses were derived from Free Software licenses. It is these licenses which are popularised widely undermining the importance of ideology of Free Software.
In the age of data the underlying license matter since its not just about using, modifying or redistributing the software but also the data which is generated using the software. Take for example Android OS the underlying software starting from Linux kernel to various apps though released under some sort of Free Software or OSS license the data that is generated or consumed is not protected or is not in the interest of the user along with some parts of the software like drivers for modem, camera various sensors. When a user first switches on the smart phone a series of Agreements show up and we are forced to agree them without which the full potential of the smart phone can not be used. Though in the recent times Google, Facebook, Apple claim that they are very concern about privacy of the user but in the license agreements that they claim to take user data and store it with them. Users don’t have a choice or even if a choice is given its hard for a normal users to opt out of the situation where these companies collect data.
Free Software licenses on the other hand are more user/developer centric and give more flexibility for the user/developer to not only develop the software but also protect user privacy. The core freedoms that govern Free Software licenses are.
Free Software means users have four essential freedoms:
(0) to run the program of any purpose,
(1) to study and change the program in source code form,
(2) to redistribute exact copies, and
(3) to distribute modified versions.
Software differs from material objects—such as chairs, sandwiches, and gasoline—in that it can be copied and changed much more easily. These facilities are why software is useful; we believe a program's users should be free to take advantage of them, not solely its developer.
Software licenses can be broadly categorised in this way
GPL-Compatible Free Software Licenses
These licenses qualify as free software licenses, and are compatible with the GNU GPL like.
GNU General Public License (GPL) version 3
This is the latest version of the GNU GPL: a free software license, and a copyleft license. We recommend it for most software packages.
Please note that GPLv3 is not compatible with GPLv2 by itself. However, most software released under GPLv2 allows you to use the terms of later versions of the GPL as well. When this is the case, you can use the code under GPLv3 to make the desired combination.
GNU General Public License (GPL) version 2
This is the previous version of the GNU GPL: a free software license, and a copyleft license. There are some limitations which are covered under GPL v3 and it is always recommended to use GPL v3 instead of GPL v2.
GNU Lesser General Public License (LGPL) version 3
The GNU Project has two principal licenses to use for libraries. One is the GNU Lesser GPL; the other is the ordinary GNU GPL. The choice of license makes a big difference: using the Lesser GPL permits use of the library in proprietary programs; using the ordinary GPL for a library makes it available only for free programs.
GNU Affero General Public License (AGPL) version 3
This is a free software, copyleft license. Its terms effectively consist of the terms of GPLv3, with an additional paragraph in section 13 to allow users who interact with the licensed software over a network to receive the source for that program. We recommend that developers consider using the GNU AGPL for any software which will commonly be run over a network.
Other noteworthy licenses include Apache License, Version 2.0, FreeBSD license (This is the original BSD license with the advertising clause and another clause removed.), Mozilla Public License (MPL) version 2.0
GPL-Incompatible Free Software Licenses
The following licenses are free software licenses, but are not compatible with the GNU GPL.
Affero General Public License version 1, Apache License, Version 1.1 and below, Eclipse Public License Version 2.0 and below
Nonfree Software Licenses
The following licenses do not qualify as free software licenses. A nonfree license is automatically incompatible with the GNU GPL.
Apple Public Source License (APSL), version 1.x, Microsoft's Shared Source CLI, C#, and Jscript License.
Licenses For Documentation
These licenses cover for documentation of the software.
Free Documentation Licenses
GNU Free Documentation License, FreeBSD Documentation License
Licenses for Works of Practical Use besides Software and Documentation like artwork images, music, videos etc.
GNU General Public License
The GNU GPL can be used for general data which is not software, as long as one can determine what the definition of “source code” refers to in the particular case. As it turns out, the DSL (see below) also requires that you determine what the “source code” is, using approximately the same definition that the GPL uses.
GNU Free Documentation License
The GNU FDL is recommended for textbooks and teaching materials for all topics. (“Documentation” simply means textbooks and other teaching materials for using equipment or software.) We also recommend the GNU FDL for dictionaries, encyclopedias, and any other works that provide information for practical use.
Creative Commons Attribution 4.0 license (a.k.a. CC BY)
This is a non-copyleft free license that is good for art and entertainment works, and educational works. It is compatible with all versions of the GNU GPL; however, like all CC licenses, it should not be used on software.
Creative Commons publishes many licenses which are very different. Therefore, to say that a work “uses a Creative Commons license” is to leave the principal questions about the work's licensing unanswered. When you see such a statement in a work, please ask the author to change the work to state clearly and visibly which of the Creative Commons license it uses. And if someone proposes to “use a Creative Commons license” for a certain work, it is vital to ask “Which Creative Commons license?” before proceeding any further.
Creative Commons Attribution-Sharealike 4.0 license (a.k.a. CC BY-SA)
This is a copyleft free license that is good for artistic and entertainment works, and educational works. Like all CC licenses, it should not be used on software.
CC BY-SA 4.0 is one-way compatible with the GNU GPL version 3: this means you may license your modified versions of CC BY-SA 4.0 materials under GNU GPL version 3, but you may not re-license GPL 3 licensed works under CC BY-SA 4.0.
Many of the parts of this write-up are taken from these links:https://www.gnu.org/licenses/license-list.html
(Bhuvan Krishna is the General Secretary of Swecha, and the lead developer of e-Swecha)