Fields are the building blocks of Drupal's powerful content modeling system. The field API allows for the development of custom field types to suit almost any data display and collection needs. Developers can create custom field types that can be bundled together and attached to various pieces of content. Fields allow a Drupal Site Administrator to create an information architecture that matches the needs of each individual site.
This series will provide you with all the information you need to be able to define a custom field in your own module. After completing all the lessons in this series, you should have a firm grasp of the Drupal 7 field API and the tools and knowledge you need in order to define your own custom field types.
This series requires an understanding of PHP and basic Drupal 7 module development. For a refresher, or if you get stuck, check out our Drupal 7 Module Development series.