The custom functionality of WordPress sites is powered by plugins and widgets. A plugin is a component that extends the core WordPress features, while a widget is a component that's used to display content or add functionality to a specific area of the layout. The ability to create and customize plugins and widgets is the key to developing advanced sites.

This chapter focuses on creating custom widgets and plugins while extending the existing features using these components. In this chapter, you will learn about the importance of plugins and widgets, how they fit into WordPress, and how you can use them to build real-world requirements. You will be building, modifying, and extending plugins and widgets to understand how they work with WordPress' core features. Also, you will learn how to resolve conflicts related to plugins. The techniques that will be discussed in this chapter will be used commonly in the upcoming chapters to build advanced site functionality.

In this chapter, we will learn about the following recipes:

• Managing widgets in widget areas
• Creating a simple widget from scratch
• Creating additional widget areas
• Displaying conditional widgets with built-in tags
• Displaying widgets inside of posts and pages
• Modifying plugin files with the built-in Plugin Editor
• Manually deactivating plugins
• Working with custom PHP code
• Customizing WordPress plugins with actions and filters