A software license is a contract that governs the use and/or redistribution of software. Today, a lot of software is developed using open-source software. Open-Source software is typically licensed under an open-source license that permits users to study, use and modify the code.
Developers sometimes run into trouble when they develop applications and they are not sure as to the license that applies to their situation. The developer may have a created a proprietary application and does not want to release the source code for the application.
Some of the common software licenses used in open source community include the Apache License and the GNU General Public License.
An example of a use of the Apache license is in the Android Open Source Project. Mobile applications developed for the Android Open Source Project are preferably licensed with the Apache Software License, 2.0 (“Apache 2.0) and the majority of the Android software is licensed with Apache 2.0.
Examples of free software programs licensed under the GPL include the GNU Compiler Collection (GCC) and the Linux kernel.
What does development of software under these various software licenses mean?
Well for starters, the Apache License allows the user of the software to use the software for any purpose, distribute, modify and distribute modified copies of the software under the license. An important feature of the Apache License is that modified source code may be distributed with a different license.
The GNU GPL differs from the Apache license in that modified software that is distributed must be distributed with its source code or the source code for the modified software must be made available. This framework is a tenet of the copyleft system is and ensures that software is free and modified distributed software is free. Free does not mean freedom from being charged but instead it means that the User is free to modify and distribute copies of the modified software once they comply with the license and incorporate the terms of the software license into their new work.