How Drupal 8 builds your pages?
Have you ever wondered what happens when a HTTP request reach your Drupal web site? How does Drupal find the correct code to execute? Which parts of the page come from the cache and which ones are built from scratch? Which queries are executed against the database? And, why not, how many time and memory the request requires to be converted in a response?
Whether if you are a contrib developer or a simple curious person the answers to those questions will let you better understand how Drupal 8 works.
The Webprofiler module can help you in understanding how all the new fancy things in Drupal 8 interact to convert a request in a response. Webprofiler collects data during the construction of each page of the site and lets you to easily explore the internals of Drupal 8.
Follow the journey of a request entering the stack middleware, passing the routing component and the controller through the ViewSubscriber and Twig. Discover how services provides functionalities and how events give the opportunity (o the chance) to write decoupled code. All without forgetting the performance and keeping an eye on memory, time, cache, queries.