CamelCase is used in some wiki markup languages for terms that should be automatically linked to other wiki pages. This convention was originally used in Ward Cunningham's original wiki software, WikiWikiWeb, and can be activated in most other wikis. Some wiki engines such as TiddlyWiki, Trac and PMWiki use it in the default settings. They also usually provide an option or plugin to disable it. Wikipedia used to use CamelCase linking. However, they have switched to explicit link markup using square brackets and many other wiki sites have done the same. Some wikis that do not use CamelCase linking may still use the CamelCase as a naming convention, such as AboutUs.