API Guide > Command plug-ins >

# Overview of adding commands to Maya

## Plug-ins

The API supports several different types of plug-ins:

- Command plug-ins—commands that extend the MEL scripting language.
- Tool commands—plug-ins that take mouse input.
- "Dependency graph plug-ins"—plug-ins that add new operations, such as dependency graph nodes. For more information see Overview of dependency graph plug-ins.
- Device plug-ins—plug-ins that allow new devices to interact with Maya.

## Command plug-ins

This chapter describes the following command plug-in topics:

- MFnPlugin
- initializePlugin()
- uninitializePlugin()
- MPxCommand
- MPxContext
- MPxContextCommand
- MPxToolCommand