Free license

A free license or open license is a license that allows copyrighted work to be reused, modified, and redistributed. These uses are normally prohibited by copyright, patent or other intellectual property laws. The term broadly covers free content licenses and open-source licenses, also known as free software licenses. The concepts originated in the free software movement and spread to other fields, including free content (such as art, writing, and music, as with Creative Commons licenses) and open-source hardware.

Intellectual property (IP) laws restrict the modification and sharing of creative works. Free licenses use these existing legal structures for an inverse purpose. They grant the recipient explicit rights to modify, reuse, and distribute the covered material. Broadly they fall into two main categories: permissive and copyleft. Both grant permission to change and distribute content, typically requiring attribution. Permissive licenses began in academia, and Copyleft licenses began in the free software movement. Copyleft licenses also require derivative works to be distributed under a similar license, often the same license. Since the mid-2000s, courts in multiple countries have upheld the terms of both types of license.