Piwik is an open platform. Being a platform has the advantage that Piwik can be extended and customised using Plugins. By default Piwik comes with 40+ plugins which are officially maintained by the core team.
Since the release of Piwik 2.0 and the launch of the Piwik Marketplace, the Piwik developer community at large is now also building plugins that let you do more with Piwik! You can find all these plugins on the Marketplace.
Besides those Plugins that we bundle with the Piwik Platform, and besides those Plugins available on the Marketplace, there are also other kinds of Extensions (or sometimes called Add-ons or Modules or Plugins) that may be useful to you. These modules help you integrate Piwik into your Website. There are such modules for most of the popular tools:
We have exciting plans for the Piwik platform, stay tuned, and keep your feedback coming!