Open license

Definition
An open license "grant[s] permission to access, re-use, and redistribute a work with few or no restrictions."

Overview
A license is open if it satisfies the following conditions:


 * Reuse. The license must allow for reproductions, modifications and derivative works and permit their distribution under the terms of the original work. The rights attached to the work must not depend on the work being part of a particular package. If the work is extracted from that package and used or distributed within the terms of the work's license, all parties to whom the work is redistributed should have the same rights as those that are granted in conjunction with the original package.
 * Redistribution. The license shall not restrict any party from selling or giving away the work either on its own or as part of a package made from works from many different sources. The license shall not require a royalty or other fee for such sale or distribution. The license may require as a condition for the work being distributed in modified form that the resulting work carry a different name or version number from the original work. The rights attached to the work must apply to all to whom it is redistributed without the need for execution of an additional license by those parties. The license must not place restrictions on other works that are distributed along with the licensed work. For example, the license must not insist that all other works distributed on the same medium are open. If adaptations of the work are made publicly available, these must be under the same license terms as the original work.
 * No Discrimination against Persons, Groups, or Fields of Endeavor. The license must not discriminate against any person or group of persons. The license must not restrict anyone from making use of the work in a specific field of endeavor. For example, it may not restrict the work from being used in a business, or from being used for research.

Source

 * Project Open Data (full-text).