Creative Commons (CC) is a non-profit organization headquartered in Mountain View, California, United States, devoted to expanding the range of creative works available for others to build upon legally and to share. The organization has released several copyright-licenses known as Creative Commons licenses free of charge to the public. These licenses allow creators to communicate which rights they reserve, and which rights they waive for the benefit of recipients or other creators. An easy-to-understand one-page explanation of rights, with associated visual symbols, explains the specifics of each Creative Commons license. Creative Commons licenses do not replace copyright, but are based upon it. They replace individual negotiations for specific rights between copyright owner (licensor) and licensee, which are necessary under an "all rights reserved" copyright management, with a "some rights reserved" management employing standardized licenses for re-use cases where no commercial compensation is sought by the copyright owner. The result is an agile, low-overhead and low-cost copyright-management regime, profiting both copyright owners and licensees. Wikipedia uses one of these licenses.
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The following are worth looking at in order to fully understand various aspects of Creative Commons licences.
There are thousands of free images,architectural designs, artifacts, graphs, maps, artworks, photographs, video clips, texts, educational works, etc. on the Creative Commons website - see link below. There are various licenses to choose from. Read their conditions carefully. You may want to use one of these licenses yourself.
Material under Creative Commons licenses may be included in theses and dissertations, as long as the conditions of the license are abided by and that the non-commercial license does not apply. The non-commercial license is complicated and before selecting one for yourself, take advice from someone who knows how this license is applied, either an IP lawyer or someone from Creative Commons itself.
Creative Commons licenses are irrevocable, so make sure you are selecting the correct one if you want to publish your works under one of these licenses. The Non-Commercial licenses may present problems, if, at a later stage, you wish to publish commercially. It would be best to seek advice from Creative Commons themselves, alternatively, your Legal Advisor, before adopting the Non-Commercial licenses.
In the broadest sense, all original work is protected under copyright. However, works in the public domain are in most cases not protected by copyright and may be used "freely". Creative Commons fall somewhere in between. Works licensed under Creative Commons may be used without permission, but only in certain instances.
Consult the following to find out more.