Applications
As you've learned from the Programming feature it's possible to put code inside XWiki pages. You can combine several pages together to form an application. In other words an application is simply a self-contained set of XWiki pages. You can export these pages into a single archive file named a XAR (it stands for XWiki Archive) which can then be imported again into other wikis. This is a very nice way to create reusable applications.
Applications offer a powerful way to create advanced content within wiki pages.
Example Applications
Calendar Application
Screenshot of the Calendar Application
Meeting Manager Application
Screenshot of the Meeting Manager Application
Bulletin Board Application
Screenshot of the Bulletin Board Application
Polls Application
Screenshot of the Polls Application
List of Applications available for download on XWiki.org
Check the Extensions wiki which lists all applications available that you can install in your wiki.
Creating new Applications
If you'd like to create new applications with XWiki our Developer's Guide will help you through the process.
If you are interested in participating to the XWiki project development itself or in building it from sources, you should refer to the Community wiki.
If you still have questions you may subscribe to the mailing lists.
Plugins
Plugins are a powerful way to extend XWiki's intrinsic features. Actually lots of the XWiki features you can see are brought by plugins bundled with the XWiki distributions.
Using a Plugin
First check the Extensions wiki to find a Plugin you'd like to use. Then copy its JAR (Plugins are bundled as JARs) into your XWiki installation: drop it in XWiki WAR's WEB-INF/lib directory. You'll need to restart XWiki for it to take effect. Please note that this is an administrative task so you'll want to ask your wiki admin for help in doing this.
Developing a Plugin
If you'd like to develop a plugin please check the plugin development tutorial.
If you still have questions you may subscribe to the mailing lists