For developers, we’ve got lots of goodies packed under the hood that you can use to extend WordPress in whatever direction takes your fancy.
Plugin System
The WordPress APIs make it possible for you to create plugins to extend WordPress. WordPress’s extensibility lies in the thousands of hooks at your disposal. Once you’ve created your plugin, we’ve even got a plugin repository for you to host it on.
Theme System
Create WordPress themes for clients, customers, and for WordPress users. The WordPress API provides the extensibility to create themes as simple or as complex as you wish. If you want to give your theme away for free you can give it to users in the Theme Repository
Application Framework
If you want to build an application, WordPress can help with that too. Under the hood WordPress provides a lot of the features that your app will need, things like translations, user management, HTTP requests, databases, URL routing and much, much more.
Custom Content Types
WordPress comes with default content types, but for more flexibility you can add a few lines of code to create your own custom post types, taxonomies, and metadata. Take WordPress in whatever direction you wish.
The Latest Libraries
WordPress comes with the latest script libraries for you to make use of. These include jQuery, Plupload, Underscore.js and Backbone.js. We’re always on the lookout for new tools that developers can use to make a better experience for our users.
Laxman Prajapati 