About Wiki Software
Wiki software is a collaborative system. This just means that it allows groups of people access to the system through a common interface. In the case of wiki software it allows the creation and editing of pages through the user’s browser.
For example, Confluence describes its wiki software as an enterprise level wiki that makes it easy for the team members to collaborate, share, and find knowledge. It provides security, easy install, and other features.
Naturally wiki software is going to come in a variety of flavors, from the very basic to full fledged content management systems. Wiki systems tend to favor content over style or blog like features.
Wiki software can be interpreted as the entire software suite to run the system or just an individual piece of it. For example, to run wiki software, entirely or a piece, a server is required, typically Apache. So the entire system would be the apache server and all the wiki software pieces. Of course, a bundled system is a little easier to install.
The majority of wiki engines are under the open source license, meaning they’re free for most purposes, much like Linux. Companies can, of course, add value to the package, such as: a slick install system, extra proprietary functionality, etc. and charge for it.
Mediawiki, for example, offers a free system which is used by the Wikimedia foundation as well as a variety of other wikis.
A list of wiki software, good and bad, can be found on the Wikipedia. The list also includes comments about the different wiki pieces as well as appropriate links.
ZDnet has a few things to say on the subject of finding the right wiki software. They suggest asking some questions first: do you want to host it, hack it, pay for it yourself? Depending on what you want to do with it you’ll be choosing different packages.