MooTools includes a number of components, but not all need to be loaded for each application. Some of the component categories are:

► Core: A collection of utility functions that all the other components require.

► More: An official collection of add-ons that extend the Core and provide enhanced functionality.

► Class: The base library for Class object instantiation.

► Natives: A collection of JavaScript Native Object enhancements. The Natives add functionality, compatibility, and new methods that simplify coding.

► Element: Contains a large number of enhancements and compatibility standardization to the HTML Element object.

► Fx: An advanced effects-API to animate page elements.

► Request: Includes XHR interface, Cookie, JSON, and HTML retrieval-specific tools for developers to exploit.

► Window: Provides a cross-browser interface to client-specific information, such as the dimensions of the window.