Each license begins as a traditional legal tool, in the kind of language and text formats that most lawyers know and love. This is called the Legal Code layer of each license.
Human Readable Deed
Since most content creators are not 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. The Commons Deed itself is not a license, but rather a user-friendly interface for communicating a particular license.
Machine Readable Metadata
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, discover, 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.
Six Types of Creative Commons Licenses