WordPress is an open source content management system running on PHP and MySQL, and often used as a blog engine. WordPress questions about programming and administration are best asked on http://wordpress.stackexchange.com/
WordPress is a PHP-based, open source content management system (cms) for creating websites and blogs. Through its dynamic presentation of content, webmasters have the flexibility to create beautiful and useful websites easily. Through its system of filters and hooks, WordPress allows developers to extend functionality through pieces of code called functions, which can be grouped into separate executables called "plugins".
WordPress as a content management platform should be distinguished from wordpress.com, which is a hosted solution by the creators of WordPress. For a discussion of the differences, visit WordPress.com and WordPress.org. The latest version is v3.9.2 release on August 6, 2014.
- WordPress Development Stack Exchange
Stack Exchange's dedicated WordPress site. Questions about programming themes, drop-ins and plugins and about the administration of WordPress are on topic there.
The main site where you can download the code, plugins and themes. There is also a forum.
- WordPress Codex
Documentation wiki with lots of good tutorials, references and links.
- Make WordPress
Official resources to help people develop for WordPress.
- WordPress Mailing Lists
21 lists to discuss nearly every aspect of WordPress.
- WordPress Trac
Bug tracker for WordPress. Useful to keep on track of the latest changes – and to report the bugs you found.
- WordPress Chat
Here you may sometimes get help very fast.
- Installing WordPress
Installing WordPress & getting started.
- Writing a Plugin
WordPress Plugins allow easy modification, customization, and enhancement to a WordPress blog.
- Plugin API
Article is specifically about the API of "Hooks", also known as "Filters" and "Actions", that WordPress uses to set your plugin in motion.
- Theme Development
WordPress themes are easy to create and make it useable. WordPress has it's own tutorial site, where everyone can educate themselves, beginner or expert.
- WordPress Multisite
You have the ability to create a network of sites by using the multisite feature. This article contains instructions for creating a multisite network.