On there most basic level, a commons refers to one way in which an institution determines the rights to a) access, b) use, and c) control its resources (Benkler 60). The obvious alternative form is the property-based system. As Benkler puts it, the fundamental difference between the two is as follows: "No single person has exclusive control over the use and disposition of any particular resource in the commons" (Benkler 60). James Boyle of Duke University defines common-based in a more media specific context as, "a form of media that is not tightly controlled by property rights, by rules, by ownership, by direct technical controls." But this does not necessarily mean that anyone who wants to can use/access/control said resource nor does it mean that he can do so as he sees fit without having to respect certain rules. Commons vary in terms of how heavily they regulate who can have access to a particular resource and how one can use/control it.
On one end of the spectrum would be a totally "open-access" commons in which there is no higher authority to control who uses it (which in a property-based system often means charging money for it) or how they use it. A completely "open" commons is hard to find. One explanation for this scarcity that Benkler touches on is this notion of "social-conventional" restrictions (Benkler 62). In less cryptic terms, people often regulate themselves simply because that's how they were raised or because they don't want to be looked down upon by others. Take our dining halls, for example. There is no militant dishwasher holding a gun to our heads screaming "don't take plates to your room and not return them," but I usually bring them back because I know I personally hate it when I have to eat pasta with a spoon and I'm sure others do too. Most people aren't economists, but they still understand the concept of "rival" goods. The e-mails threatening to cancel midnight breakfasts if dishes aren't returned are constant reminders that "open-access" is a privilege and can be revoked if abused. But while there is a finite supply of plates in the dining halls, ideas cannot be "overfished" as James Boyle of Duke University puts it. This is one of the primary arguments in favor of commons-based media.
On the other hand of the spectrum there is what Benkler calls "limited-access" commons (61). This MediaWiki that we are editing is a perfect example of such a system. For one thing, we can't even edit this without first entering our Middlebury user name and password. Access is further limited to members of our class (I think - correct me if i'm wrong). Secondly, certain pages are locked from editing...if I wanted to add another term to the list that I feel needs to be there, I am physically prevented from doing so by the "formal" restraint of the software itself. Not too mention there are a variety of conventions held amongst wiki editors in terms of things like tone and style that I personally find restricting.
Another example of a limited-access commons is one where permission to use media is not restricted to certain parties, such as the creator, site administrator, or rights holder, but to certain uses of the media itself. Fair use is an example of this, but because it is difficult to define and some media creators wish to make their media more open to re-invention, other systems of creator rights protection, such as the Creative Commons have been formed. The aim of this system is to provide custom licensing whereby media producers can reserve, not only all or none of the rights to their work, but only those rights they wish to. The Creative Commons organization states on their website: "Creative Commons provides free tools that let authors, scientists, artists, and educators easily mark their creative work with the freedoms they want it to carry. You can use CC to change your copyright terms from "All Rights Reserved" to "Some Rights Reserved."" (Website content licensed under an Attribution 3.0 Unported License  ) The rights one can reserve or waive under the Creative Commons include: attribution, non-commercial use, no derivative works, and permission to distribute derivative works only under a like license. This alternative to the extremes of copyright and public domain is meant to stimulate creativity and reinvention of old work, as well as to protect the desired willingly claimed by the original creators.
Despite the varying level of constraint amongst commons-based system, the rules are the same for each and everyone of us, except in the case of custom licensing, which mixes and matches a pre-set selection of such regulations. As Benkler points out, these restrictions are "symmetric" for every user (62). One final distinction that must be made is that while peer production is inherently a common based system, not everything that is commons based is an example of peer production. Refer to that article for clarification.
Yochai Benkler, The wealth of networks : how social production transforms markets and freedom (New Haven: Yale University Press, 2006)
Creative Commons