MET:Wiki Affordances

From UBC Wiki

This page originally authored by James Cash (2009).

All wiki systems have been designed around a similar conceptual model, that is, any person visiting any page in the wiki has the ability to quickly and easily edit the content of that page in the browser window. This is the core affordance of modern, fully developed wikis such as MediaWiki. However, there are five core affordances that all modern, fully developed wikis share. This article contains a review of these affordances.


Wikis are web sites in which the content pages in the site can be edited quickly by the any user of the web site. Wikis are almost universally mentioned in the various definitions of Web 2.0 (e.g., O'Reilly, 2005). Simply put, Web 2.0 is the name often put forth to describe the current era of World Wide Web in which its information is dynamic rather than static.

Ward Cunningham was the author of the first wiki software called WikiWikiWeb. His list of original design principles summarize many features common to most wiki design models.

Design concepts


In his book, The Design of Everyday Things, Donald Norman (2002) outlines a comprehensive set of design principles that can be used to analyze systems or to design systems. In particular, the concept of affordances, especially as it applied in HCI environments, was further clarified (1999). According to Norman, the most misunderstood design concept is that of affordance. It is best understood by example. When a programmer conceives of a software feature (for example, the ability to edit a web page you are viewing, or the ability to view the version history of an article in a wiki) that feature, possibility, or capability is called an affordance. They don't really physically exist. You cannot touch an affordance; the notion is more akin to an idea than an object, either physical or virtual. If a user sees through the screen design that a certain feature exists, and has an idea of the possibilities of that feature, that is termed a perceived affordance. The actual iconic image or text on the screen (e.g., edit tab in MeidaWiki, or the edit button in other wikis) is what Norman calls a cultural constraint, that is, a shared and understood convention known to a group of users that helps them to interact with the system and successfully employ the affordance.

One strategy used by many software designers is to add as many affordances as possible in order to make the software more useful and more universally applicable. Despite the many advantages of this idea, users can quickly become overwhelmed or confused with perceived affordances, especially if they are 'advertised' with buttons, links and tabs all over the GUI. Managing affordances in feature-packed wiki systems is a significant issue. However, despite the many new affordances that now exist, and that will be added to wiki systems in the future, there will always remain five core affordances that are the defining features of modern wikis.

Comparing wiki affordances lists, as of February 2009, 131 wiki engines available online. Cunningham's site lists 145 wikis available. A common assumption, due to this large number of wiki systems, is that there must be many kinds of wikis for many different purposes. This may be partly true but most wikis share a common set of affordances.

Available wiki engines should be characterized not so much by what they can do (they are all wikis!) but what do they do besides being wikis, and what added value does each package bring. For example, some wikis are commercial, some are free. Some wikis have dedicated support personnel to help you, some do not... and so on. The WikiMatrix website was designed to allow users to quickly and easily compare the vast array specifications and added value features of the wikis in its database.

Core affordances of wiki systems

After a close examination of the currently available wiki engines (using data from, it is clear that most share a common set of five core affordances:

  • Editable - web page content can be quickly and easily edited by anyone visiting the page
  • Markable - textual content can be marked up in order to add structure (e.g., links, tables, images)
  • Versionable - previous versions of the page are archived, viewable, and usable
  • Accountable - changes made to a page can be traced to a user name or IP number
  • Discussable - editor collaboration is facilitated by a discussion system

There are some minor exceptions, such as the deliberately minimalist wiki engine MicKI, which do not include all five affordances.

It should be noted that modern wikis have far more affordances than these. In fact, many are fully extensible and developers freely and openly share the code so that extensions can be properly and efficiently designed and tested. However, the five core features outlined below form the base set of affordances that are common to most modern wiki systems.


This affordance is arguably the defining feature of a wiki so long as it is quick, easy and available to everyone visiting the page. These three qualifications are inexorably linked to this affordance and distinguish wikis from other kinds of dynamic web pages, such as blogs. The editable affordance is made possible by the general Web 2.0 affordance of XML/CSS.

In the early days, web pages were hand coded in HTML (and later using WYSISYG HTML generators) and uploaded to a web server via ftp. This was not a quick or easy process. In addition, web pages were static and lacked any genuine interactivity. As web servers began to support CGI, web pages grew a little more interactive. With CGI, for example, users could add text to forms and send that information to the server for processing. However, web pages were still static: users still could not change or edit the content of the web page itself.

The beginning of the writable web occurred when the content of web pages could be separated from its formatting codes. Now, instead of content that was simply marked up with code (HTML), content was now classified and defined with XML. This content could now be used by a web server running a scripting language, such as PHP, and, using formatting styles (e.g., CSS) to display the content in whatever form that was required. The web server generates these pages as needed. Web pages no longer existed as before! The conceptual model of a file system with interlinked, prewritten, stored HTML files was abandoned.

The video (left) was created by Dr. Michael Wesch of Kansas State University. It is a fairly well-known video which explains Web 2.0 affordances such as XML.

The ease and speed with which wiki content can be edited is completely due to this change in conceptual model involving the separation of content and form. Because web pages in this new model are created on the fly, users can change the content of a page, along with some basic formatting, quickly and easily.

Wikis and blogs share this affordance which allows quick and easy editing of content on the fly. But wikis are not blogs. The conceptual model of each is fundamentally different. The model for a blog is based upon a single author creating the content whereas the model for a wiki is based upon the collaborative authorship of an almost unlimited number of people. This basic difference of shared authorship echoes in all other affordances of the wiki system.


Content added to a wiki can be as simple as a blog comment or it can include complex formatting such as tables and embedded media. Therefore, wikis allow a common and expected affordance of a text formatting via toolbar or integrated WYSISYG editor. However, this is where the similarities between wikis and blogs end.

The markable affordance of wikis extends far beyond basic text and page formatting. For example, most mature wikis include both template and category features. Templates are prewritten content that can be used on multiple pages without the author having to type in the content. In a way, they are analogous to a rubber stamp but they can contain interactive functionality which makes them quite a bit more useful. Another way to think of wiki templates is to imagine a kind of macro object.

Categories are used in wikis to help structure the vast array of articles. What is interesting is that it is the editors of the wiki that add the articles to one or more categories. This allows for an almost limitless freedom in the way wiki information is structured by its authors. It also allows for multiple interpretations of the way information can be organized.

File:EDIT MediaWiki.png File:EDIT DekiWiki.png
MediaWiki's toolbar based editing window
where content can be added and formatted.
DekiWiki's WYSIWYG editing window where
content can be added and formatted.


I use the term versionable to describe the affordance that sets wikis apart from all other kinds of web content. Most mature wikis have version control or article history affordances built into the system. This is a very important and necessary affordance for many reasons. First, because the conceptual model of a wiki is based upon collaborative authorship involving a large number of potential authors, there must be a way to store previous versions of articles so that content is ultimately never lost. People who are new to wikis are often unaware that all versions of articles remain in the database system and that all information ever added to the wiki is still accessible in some form. Once this affordance is fully realized by a wiki user, any fear of accidentally deleting content during editing is overcome. Wiki editors come to know that any edits they make can be deleted or restored with the click of a few buttons. Some wikis extend this affordance by allowing an editor to label a specific version with a summary of what was changed in that version. These edit summaries usually appear alongside each listed version in the article history list.

However, there is a deeper significance to this affordance that is only beginning to be realized. Social scientists, cultural anthropologists, and philosophers can now directly study the creation of knowledge artefacts over time, or in real time. The fact that wikis have the versionable affordance allows any users to study the complete development of an article. For example, at any time when there is a significant event occurring in the real world, there is, almost invariably, a Wikipedia article also being created at the same time, in real time. In fact, Wikipedia has a well known template that editors tag onto the top of such articles: This article documents a current event. Information may change rapidly as the event progresses. These are fascinating articles to watch during the event. Sometimes hundreds of editors are working simultaneously to add details, references, information sources, quotes, and corrections about such an event. Some have noticed that the Wikipedia article becomes a focal point of current information whose speed and currency is unmatched, even by news organizations.

The following videos are animations made from screenshots of Wikipedia version histories of articles that document two horrific recent events. The animation on the left shows the evolution of the July 7, 2005 London Bombings article and the animation on the right shows the evolution of the 2007 Virginia Tech massacre article. (Any person can view the evolution of any Wikipedia article by simply viewing the history of the article, starting at the earliest edit, and moving forward one version at a time.)

The animation on the left was created by using a program called Wikipedia Animate by Dan Phiffer. (Some other "Wikipedia version history animators" can be found here.) After installing one extension and one script to Firefox, an animate button is added to Wikipedia's history pages. The versionable affordance allows for this kind of imaging to be possible. It is interesting to look at but not that informative or insightful. Far more interesting than a mere animation of how the appearance of an article changed over time would be an in-depth analysis of the content that was added/changed/deleted with each successive edit.


The affordance of accountability on a wiki system means nothing more than any changes to content can be traced to a specific author, known by either a user name or by an IP number. This affordance of accountability should not be confused with the ethical consideration of accountability although they are obviously related. The affordance only allows users to know who was responsible for the content added, changed or deleted. (The issue that authors take responsibility for their content is another issue and is not discussed here. However, interested readers can view an excellent and recent discussion (Tollefsen, 2009) regarding group vs. individual testimony in Wikipedia articles.)

This affordance goes hand in hand with the final affordance discussed below, that of discussability. Users cannot discuss content with one another without knowing who is responsible for that content. However, most modern wikis, including Wikipedia, allow anonymous users to edit and allow registered users to edit with nicknames. In both cases, the real world identity of the editor is unknown. There is a balance struck between anonymity and collaboration. Registered wiki editors enjoy the anonymity they have when editing but they also enjoy the collaborative aspects of discussability.


Discussability is an incredibly important affordance of wikis that is interwoven into the structure of the content and the administration of that structure. All major wikis include this affordance which allow editors a meta-article, or forum space, that is attached to every article in the wiki. In this way, the article remains useable by readers by storing the discussion about its content separately. The discussion namespaces are places where the mechanics of social constructivism (Schunk, 2004) come into play. The article represents the knowledge artifact that is being constructed whereas the discussion pages explicitly record the decision mechanisms governing the inclusion or exclusion of information.

Many wikis also offer something called namespaces. A namespace is an information structure affordance embedded into the design of the wiki. For example, in MediaWiki, the main, or article, namespace is the set of data that includes all articles and discussion pages relating to those articles. There is also a MediaWiki namespace in which there are administrative articles containing such information as official policies, help and instructions, essays, notice boards, help desks, and so forth. The other major namespace in MediaWiki is the user namespace. Every major namespace is paired with a discussion namespace so that a separation exists between article content and content relating to a wiki’s policy or content relating to discussions about policy or content related to discussions about the articles themselves.

Wiki affordances: Implications

Democracy. The implications of a wiki system were apparent from the beginning (Leuf & Cunningham, 2001). That is, the affordances in the wiki design democratized the content stored in a wiki so long as any visitor was allowed to edit the site. Wikipedia is the obvious example. It is the largest encyclopedia ever created in terms of words, article quantity (currently 2.7 million articles [1]), or any other metric you wish to use. It's accuracy is comparable to that of Encyclopedia Britannica's (Giles, 2005).

Recent criticisms based on an editor activity analysis leveled against the democracy of Wikipedia are misleading. Wilson (2008) argues that 1% of all Wikipedia users are doing 50% of the work. He concludes that that fact demonstrates a lack of democracy. However, 1% of current, registered Wikipedia users [2] amounts to about 90,000 users. Also, in general terms, registered users are often more concerned with the administration, structure, and organization of the information than the addition of new content. It is, in fact, the masses of anonymous users that add most of the new content. Aaron Swartz, sums up his analysis of the question, "Who edits Wikipedia?" (In the following quote, Swartz refers to anonymous users as outsiders and registered, active users as insiders.)

When you put it all together, the story become clear: an outsider makes one edit to add a chunk of information, then insiders make several edits tweaking and reformatting it. In addition, insiders rack up thousands of edits doing things like changing the name of a category across the entire site — the kind of thing only insiders deeply care about. As a result, insiders account for the vast majority of the edits. But it’s the outsiders who provide nearly all of the content. (Swartz, 2006, ¶ 14)

His analysis has been taken seriously and has been confirmed by other researchers (e.g., Kittur, Pendleton, Suh & Mytkowicz, 2007). Therefore, it can be argued successfully that, when content additions is the metric (as it was in these analyses) and not edit frequency by user, Wikipedia content is not being driven by a relatively small, elite group but, rather, the masses of people who visit the site on a day-to-day basis. There are no restrictions on who can edit. Any visitor to the site can, if they choose to, edit any article. Therefore, the control of the content is in the hands of the masses.

Besides, even if it were true that a small group of Wikipedia editors were adding the majority of the content, there are no restrictions at all as to who can join that group. (Any person with a computer, browser and Internet access can edit any page.) It is even a misnomer to call it a group. The registered users on Wikipedia do not feel as though they are in a big group that "let's in" or "welcomes" some but not all. Regular Wikipedia users generally call themselves Wikipedians and fully subscribe to the notion that Wikipedia is a site anyone can edit, and edit boldly!


Giles, J. (2005). Internet encyclopaedias go head to head [Electronic version]. Nature, 438, 900-901. Retrieved February 26, 2009, from

Kittur, A., Pendleton, B. A., Suh, B., & Mytkowicz, T. (2007). Power of the few vs. wisdom of the crowd: Wikipedia and the rise of the bourgeoisie. Paper presented at the Computer/Human Interaction 2007 Conference. Retrieved February 26, 2009, from

Leuf, B. & Cunningham, W. (2001). The Wiki Way: Quick Collaboration on the Web. Boston, MA: Addison-Wesley Professional.

Norman, D. A. (1999). Affordances, conventions and design. Interactions, 6(3), 38-41.

Norman, D. A. (2002). The design of everyday things. New York, NY:Basic Books.

O'Reilly, T. (2005, September 30). What is web 2.0: Design patterns and business models for the next generation of software. Retrieved February 26, 2009, from

Schunk, D. H. (2004). Learning theories: An educational perspective (4th ed.). Upper Saddle River, NJ: Prentice-Hall/Merrill.

Swartz, A. (2006, September 4). Raw thought: Who Writes Wikipedia? Retrieved February 26, 2009, from

Tollefsen, D. P. (2009). Wikipedia and the Epistemology of Testimony [Electronic version]. Episteme. 6, 8-24. Retrieved February 26, 2009, from (n.d.). Compare them all. Retrieved February 21, 2009 from

Wilson, C. (2008, February 22). The wisdom of the chaperones: Digg, Wikipedia, and the myth of Web 2.0 democracy. Slate, Article 2184487. Retrieved February 26, 2009, from

Further reading

Ideas for further development of this article

  • The implications section near the end is very general. It would be interesting to go into greater depth about the issue of democracy on wikis as well as the concept of shared testimony discussed in Tollefsen's article.
  • It would be interesting to add an "implications" section inside each of the five affordances sections so that a specific discussion could be added that examines the ramifications of each affordance with respect to various perspectives such as pedagogy, epistemology, social constructivism, and so forth.