These pages are holistic overviews of a given API or Application Programming Interface. Each covers the functions involved in and use of a given set of functionality. Together they form what might be called the WordPress API, which is the plugin/theme/add-on interface created by the entire WordPress project.
If you've read through all of these you should have a good sense of how to extend WordPress through Plugins.
This category has the following 2 subcategories, out of 2 total.
The following 31 pages are in this category, out of 31 total.