# Extension structure

## Table of Contents

- Files which make up an extension
- Basic constructs
- The zend_module structure
- Extension globals
- Life cycle of an extension
- Testing an extension

Many extension-writing guides focus on simple examples first and ignore the requirements of more complex implementations until later. Often such guides must repeat themselves over and over in order to describe these new features. This section describes extension structure from the perspective of a mature, practical implementation, in order to prepare users for needs and issues they will almost always encounter in the process of extension development.