GPL agreement :

That versatility public license (General Public License, referred to as the GPL).

GPL with other free software licenses as license the public to enjoy: running, free copying software, free propagation software release, access to the source code of free software, free to improve the software and to make their own improved version of the spread of the social issue.

GPL also stipulates that: as long as such modifications in the text as a whole, or some part from the GPL program, modify the text of the overall circulation in accordance with the GPL must, not only to modify the text of the source code must be open to the public, and for this circulation modify the text does not permit limit themselves to make additional modifications person. Therefore, one can not follow the GPL circulation program with non-free software merger. This flow rule expressed by GPL called copyleft, represents the concept of copyright (copyright) of "odds."

GPL agreement's main principles:

1, from beginning to end to ensure that the software released as open source form, protection and development gains are not stolen for commercial sale. Any set of software, as long as the use of third-party source software protected by the GPL, and to non-developer release, the software itself will automatically be protected by the GPL entities and constraints. In other words, at which point it must be open source.

2, GPL is roughly a left side of the copyright (Copyleft, or translated as "anti-copyright" "copyright belongs to the left", "copyleft", "version responsibility", etc.) expression. You can remove all of the original copyright information, as long as you keep an open source, and with the source code, binary version of the GPL license attached on the line, so that future generations can be very clear that the authorization information for this software. GPL is the essence, as long as the complete open source software in the situation, as far as possible so that users get the space for free play, the software get faster and better development.

3, regardless of the software publisher in what form must be accompanied source code. For example, available for download on the Web, it must be binary version (if any) to download the same page, clearly provide the source code download link. If you publish on CD-ROM, CD-ROM must be accompanied source file.

4, companies or individuals to develop or maintain software developed under the GPL, you can charge a service fee to the user. But still the old saying - must provide free full source code for software, source code and do not be bundled service or any disguised bundling.

GPL details

AGPL agreement:

The original GPL agreement, due to the rise of current network services company (eg: google) had some loopholes, such as the use of free software GPL, but not with the release into the network, you can freely use the GPL open source does not own proprietary solutions. AGPL increased by the constraints of this approach.

GPL premise constraint entry into force of the "release" software that uses GPL software components via the Internet or CD-ROM release software, it must explicitly attach source code and source code and the GPL-protected products.

So if it does not "publish" on the unfettered. Such as using GPL components written in a Web system, do not publish this system, but to use this system to provide services online, while not open source code.

AGPL details

LGPL agreement:

Lesser General Public License (Lesser General Public License) or Library General Public License (Library General Public License)

Based LGPL software also allows commercial sales, but not closed source.
If you make any changes and / or re-development of the LGPL software and to be published, your product must inherit LGPL agreement does not allow closed-source. But if you follow the program of LGPL software to make any connection, calling instead contain, it allows closed source.

LGPL Details

Apache Agreement:

Apache Licence protocol is well-known non-profit organization open source Apache used. The agreement is similar to BSD and also encourage code sharing and respect the original author copyright, also allows code changes, then released (as open source or commercial software). Conditions need to be met and BSD also similar:

Users need to code an Apache Licence
If you modify the code, a description of the modified files.
Extending the code (code and source code modifications are derived) having the same code as the need in the protocol, trademarks, patents, and other statements contained in the original OF predetermined required.
If the re-release of the product is included in a Notice file, the file needs to have in the Notice Apache Licence. You can add your own license in the Notice, but not the performance of the Apache Licence to change the constitution.

Apache Licence also licensed for commercial use friendly. Users can also modify the code as needed to meet the needs and as open source or commercial product launches / sales.

http://en.wikipedia.org/wiki/Apache_License

Zlib / Libpng agreement:

The license only has the following points to be accounted for:
Software is used on 'as-is' basis. Authors are not liable for any damages arising from its use.

The distribution of a modified version of the software is subject to the following restrictions:
1.The authorship of the original software must not be misrepresented,
2.Altered source versions must not be misrepresented as being the original software, and
3.The license notice must not be removed from source distributions.
The license does not require source code to be made available if distributing binary code.

Chinese refer to the following (personal understanding)

The agreement requires compliance with the following points:

As it is based on using the software, the author is not responsible for any loss of photos into the software.

The modified version of the software will be subject to the following restrictions:

You can not distort the original software copyright
The modified software can not be misrepresented as being the original software
Content licensing agreement can not be deleted in the source code

If you can not attach binary release the source code.

http://en.wikipedia.org/wiki/Zlib_License

BSD agreement:

BSD open source license agreement is to give the user a lot of freedom. Free to use, modify the source code can also be modified code as open source or proprietary software re-release. When you publish using the BSD protocol code, or the code to BSD license to do secondary development based on their own products, we need to meet three conditions:

If the re-release of the product contains the source code, you must have the original BSD license code in the source code.
If we publish only a binary library / software, you need to include the original BSD license code in the document libraries and copyright notices / software.
You can not use open source authors / agency name and the name of the original product to do marketing.

BSD code that encourage code sharing, but the need to respect the copyright of the author of the code. BSD By allowing users to modify and redistribute the code, also allows the use or development of commercial software distribution and sales on the BSD code, so it is an integrated business-friendly agreement. Many of the companies in the selection of products when they are open source BSD protocol of choice, because you can completely control these third-party code can be modified or secondary development when necessary.

http://zh.wikipedia.org/wiki/BSD%E8%AE%B8%E5%8F%AF%E8%AF%81

MIT agreement:

MIT License name from MIT (Massachusetts Institute of Technology, MIT), also known as "X Terms" (X License) or "X11 Terms" (X11 License), MIT content clause BSD license and three (3 -clause BSD license) content is quite similar, but the software is authorized to impart greater rights to limit the fewer.

Licensee has the right to use, copy, modify, merge, publishing, distribute, sublicense and sell copies of software and software.
Licensee may modify the terms of the authorization needed for the appropriate program content.
In all copies of the software and software must include a copyright notice and permission notice.

This license does not belong to the terms of copyleft free software license that allows the use of free / open source software or free software (proprietary software). Also goes to the MIT and BSD (The BSD license, 3-clause BSD license) at a different nature. MIT provisions can coexist with other license terms. In addition, MIT provision is the Free Software Foundation (FSF) recognized free software license terms compatible with the GPL.

http://en.wikipedia.org/wiki/MIT_License

Reference: https: //my.oschina.net/yangsheng/blog/190917

Software compares various protocols (GPL, AGPL, LGPL, Apache, Zlib / Libpng, BSD, MIT)