Apache License

The Apache License is a free software license made by the Apache Software Foundation to set rules on how the software they created may be used by others. Some of these rules are about not only using the software, but also making changes to the software. All of the Apache Software Foundation's software and projects, such as the Apache HTTP Server, use this license. Some software that is not made by the Apache Software Foundation also use this license rather than trying to create another type of license on their own.
In May 2004, Google said that 25.8 percent of software projects hosted on Google Code used this license.