Routing system overview | Routing system | Drupal Wiki guide on Drupal.org
Decoupled Router | Drupal.org
Views Advanced Routing | Drupal.org
Improve installer performance by ~20% by rebuilding the router after the entire installation is complete rather than after each module [#3086307] | Drupal.org
How to develop a custom page on Drupal 8 | Anubavam
All functionality of hook_menu() is replaced by new systems for routing, menu links, local tasks, actions and contextual links | Drupal.org
Adventures in Porting a D7 Form Module to Drupal 8 | Drupalize.Me
Understanding Drupal 8 Routes and Controllers | BeFused
Drupal 8 Creating custom module from scratch - wiki
Symphony2 Components In Drupal 8 : An Integration Every Drupaler Must Know About | Specbee