User:Buidhe paid/Apache

The Apache License is a permissive free software license written by the Apache Software Foundation (ASF). It allows users to use the software for any purpose, to distribute it, to modify it, and to distribute modified versions of the software under the terms of the license, without concern for royalties. The ASF and its projects release their software products under the Apache License. The license is also used by many non-ASF projects.

History
Beginning in 1995, the Apache Group (later the Apache Software Foundation) released successive versions of the Apache HTTP Server. Its initial license was essentially the same as the original 4-clause BSD license, with only the names of the organizations changed, and with an additional clause forbidding derivative works from bearing the Apache name.

In July 1999, the Berkeley Software Distribution accepted the argument put to it by the Free Software Foundation and retired their advertising clause (clause 3) to form the new 3-clause BSD license. In 2000, Apache did likewise and created the Apache License 1.1, in which derived products are no longer required to include attribution in their advertising materials, only in their documentation. Individual packages licensed under the 1.1 version may have used different wording due to varying requirements for attribution or mark identification, but the binding terms were the same.

In January 2004, ASF decided to depart from the BSD model and produced the Apache License 2.0. The stated goals of the license included making it easier for non-ASF projects to use, improving compatibility with GPL-based software, allowing the license to be included by reference instead of listed in every file, clarifying the license on contributions, and requiring a patent license on contributions that necessarily infringe a contributor's own patents. This license requires the preservation of the copyright notice and disclaimer.

Compatibility
The Apache Software Foundation and the Free Software Foundation agree that the Apache License 2.0 is a free software license, compatible with the GNU General Public License (GPL) version 3, meaning that code under GPLv3 and Apache License 2.0 can be combined, as long as the resulting software is licensed under the GPLv3.

The Free Software Foundation considers all versions of the Apache License to be incompatible with the previous GPL versions 1 and 2. Furthermore, it considers Apache License versions before 2.0 incompatible with GPLv3. Because of version 2.0's patent license requirements, the Free Software Foundation recommends it over other non-copyleft licenses. If the Apache License with the LLVM exception is used, then it is compatible with GPLv2.