Hudson is extended through the use of plugins. Plugins integrate Hudson with a range of build, SCM, testing and other ALM/SDLC tools.
Following plugins are mandatory for Hudson (3.0.0 and newer) to work properly. They must be installed before using Hudson.
The following plugins are developed and maintained by Hudson core team. They are tested as part of the QA certification process
The following plugins are widely used plugins and are tested as part of the QA certification process
All other plugins in the Hudson Plugin Central are not QA certified. However, these plugins are auto tested to load correctly in Hudson.
The simplest way is by going to your installation's management screen and clicking Manage Plugins (http://yourhost/hudson/pluginManager/). The web interface will then download *.hpi files from here, and you will just need to restart your Hudson to pick up the changes.
Save the downloaded *.hpi file into the $HUDSON_HOME/plugins directory. You will then need to restart Hudson (many containers let you do this without restarting the container.)
Caveat: the names of the plugin directories on the download site are not always matching the name given to the plugin; common sense should apply.
Plugin developers should take a look at Hosting Hudson Plugins