# Creating custom plug-ins

In addition to adding plug-ins from the plug-in registry at dita-ot.org/plugins, you can create custom DITA-OT plug-ins of your own to modify the default output, add new output formats, support new languages, or implement DITA topic specializations.

A plug-in consists of a directory, typically stored within the plugins/ subdirectory of the DITA-OT installation. Every plug-in is controlled by a file named plugin.xml, which is located in the root directory of the plug-in.