By default, WordPress offers blogging and CMS functionalities to cater to simple applications. In real web applications, we need to develop most things using the existing features provided by WordPress. In short, all those web application-related features will be implemented using plugins. In this book, we have created a main plugin for portfolio management application. This plugin was intended to provide project specific tasks in our application and is hence not reusable in different projects. We need more and more reusable plugins and libraries as developers who are willing to take long journeys in web application development with WordPress. In this section, we will discuss the various types of such plugins: