PHP + MySQL
Ranked in these QuestionsQuestion Ranking
Pro Upgrades are smooth
Because all features of Tiki are supported by core developers, compared to a model where the wiki relies on third-party extensions that may or may not get upgraded along with the core codebase, the upgrades are a lot easier.
Pro Lots of built-in features
Tiki includes tracker, chat, newsletter, forum and much, much more functionality out of the box.
Pro Free and open source
Tiki is licensed under LGPL.
Pro It's a full featured CMS
Tiki supports user-account management, permission management, allows managing menus, customizing layout, etc.
Pro LDAP support
Con Can feel bloated
Since there's so much stuff in Tiki already built-in, it can be overwhelming if all you need is a simple wiki.