You may have noticed from previous columns that I regularly refer to the web site wikipedia.org. Wikipedia is an on-line encyclopedia that contains pages, or articles, on almost every topic imaginable. It's a great place to start any research project on the Internet. It's not uncommon to type a word into a search engine and see a page from Wikipedia in the top ten results. Try searching for something like "acid rain" or "norm abram" to see what I mean.

The web site for Wikipedia is built using a type of software called a wiki. There are many different variations of Wiki software produced by several different companies and communities. Wikipedia in particular uses the software package called MediaWiki, which is free and open source software. Using MediaWiki you can install your own wiki web site that looks and feels much like the Wikipedia site. Maintaining a knowledge base on a specialty topic would be a good use for such a wiki.

On Wikipedia, it's easy to sign up for your own account, and you can be adding or improving Wikipedia's content in seconds. Well, maybe seconds is a bit hasty. First, you will need to learn the fairly straightforward markup that helps you format the text of an article. For articles that exist already, you simply click the "edit this page" tab at the top of the page. Doing so will display an edit box containing the entire contents of the article ready for your updates. You will notice that items appearing as headings on the article page will now appear as varying numbers of equal signs around them. This is the Wiki markup for a heading, with the number of equal signs indicating the level of heading. Italic text is marked with two single quotes on either side, and bold text uses three single quotes. It's a little unusual at first, but you can use the tool bar to help you out and you get used to it after a few edits. For making small changes on Wikipedia, you can also opt to edit a single section within an article rather than the whole page. Just click the "[edit]" button to the right of the section heading. A quick change, preview and a save will make your changes visible to the whole world.

With the ease of editing and very few restrictions on who can edit which articles, you might think that people would abuse the Wikipedia system. Sadly, this has been the case in far too many instances. There are features in the software that minimize the effects of misleading article edits. For instance, all edits are logged with username and/or the IP address of the computer where the changes were made from. You can see the list of changes by going to the "history" tab. Here you will see a list of every edit made to the page, with links to see what changes were made (click the "diff" links). If there is some dispute about a change, users can defend themselves using the discussion page available for each article by clicking on the "discussion" tab. Wikipedia vandalism does occur, but is usually spotted quickly and corrected by the community or maintainers of the site.

Despite the fact that you need to be on your guard for incorrect information (you should always double check your facts anyway), Wikipedia is the shining example of how wiki software can be used to present and maintain a base of knowledge. Even if only a few people contribute, a wiki is helpful to a large audience. And in this case, the audience can correct any errors with ease and improve the experience for everyone.