OERs are built around five principles: retain; reuse; revise; remix; and redistribute. This is known as the 5R framework, proposed by David Wiley, and it defines the major characteristics of "open" content.
the right to make, own, and control copies of the content
the right to use the content in a wide range of ways (e.g. in a class, in a study group, on a website, in a video)
the right to adapt, adjust, modify, or alter the content itself (e.g. translate the content into another language)
the right to combine the original or revised content with other open content to create something new (e.g. incorporate the content into a mashup)
the right to share copies of the original content, your revisions, or your remixes with others (e.g. give a copy of the content to a friend)