eZ publish is a complex, fully object oriented application written in the PHP language. The system basically consists of three parts:

- Modules
- Kernel
- Libraries

The libraries
The libraries are the main building blocks of the system. These are highly reuseable general purpose PHP classes. The libraries are in no way dependent on the eZ publish kernel. People looking for general PHP libraries should take a look in the "lib" folder within the root directory of an eZ publish installation. Appendix A contains a complete list and a short description of the currently available libraries.

The kernel
The eZ publish kernel can be described as the system core. It takes care of all the low level functionality like content handling, workflows, version control, access control, etc. Basically, the kernel is a collection of engines, it builds upon and makes use of the libraries.

The modules
A module can be thought of as a collection of functionality. It may be described as an interface to a an engine inside the kernel. Each module has a collection of functions that take care of various tasks. Appendix B contains a complete list and a short description of the currently available eZ publish modules.