Creative Commons public copyright licenses incorporate a unique and innovative “three-layer” design. Taken together, these three layers of license ensure that the spectrum of rights isn’t just a legal concept. It’s something that the creators of works can understand, their users can understand, and even the Web itself can understand.
Each license begins as a traditional legal tool, in the kind of language and text formats that most lawyers know and love. We call this the Legal Code layer of each license.
Since most creators, educators, and scientists are not in fact lawyers, we also make the licenses available in a format that normal people can read - the Commons Deed (also known as the “human readable” version of the license). The Commons Deed is a handy reference for licensors and licensees, summarizing and expressing some of the most important terms and conditions. Think of the Commons Deed as a user-friendly interface to the Legal Code beneath, although the Deed itself is not a license, and its contents are not part of the Legal Code itself.
The final layer of the license design recognizes that software, from search engines to office productivity to music editing, plays an enormous role in the creation, copying, discovery, and distribution of works. In order to make it easy for the Web to know when a work is available under a Creative Commons license, we provide a “machine readable” version of the license - a summary of the key freedoms and obligations written into a format that software system, search engines, and other kinds of technology can understand. We developed a standardized way to describe licenses that software can understand called CC Rights Expression Language (CC REL) to accomplish this.