CakePHP comes with a plethora of built-in functions and classes. These classes and functions try to cover some of the most common features required in web applications.
General purpose libraries are available and reused in many places across CakePHP.
To learn about creating and using behaviors, read the section on Behaviors.
CakePHP has a selection of components to help take care of basic tasks in your controllers. See the section on Components for how to configure and use components.
Read Helpers to learn more about helpers, their API, and how you can create and use your own helpers.
Beyond the core MVC components, CakePHP includes a great selection of utility classes that help you do everything from webservice requests, to caching, to logging, internationalization and more.