While developing on Drupal, it is important to be able to see what is going on under the hood. Drupal 8 has enhanced capabilities here over Drupal 7, in both debugging and profiling. In this chapter, we will be covering the following:

• First, we will explore the debugging functionality built into Drupal 8 core. This will allow us to examine information from the theme layer as well as looking at how Drupal processes content.
• Next, we will install the Devel module and use it to debug our custom modules.
• Finally, we will use the Web Profiler to ensure that our site is performing well.