Have you ever wondered what happens when a HTTP request reaches 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 much time and memory the request requires to be converted into a response?
Whether you are a contrib developer or a simple curious person the answers to those questions will let you better understand how Drupal 10 works.

The WebProfiler module can help you in discovering how all the different subsystems of Drupal 10 interact to take a request and return a response. WebProfiler collects data during the build of each page of the site and lets you easily explore the internals of Drupal 10.

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 provide functionalities and how events give the opportunity (or the chance) to write decoupled code.

Knowing your system will allow you to find bottlenecks, reduce resources and lower the costs.