I'm reading in Apress' Definitive guide to Drupal 7 and I'm trying to understand what they're saying. For those who have the book, on page 404 paragraph it says - and I quote - "Every path ultimately matches up to a menu item with a page callback function that has chief responsibility for displaying the page at that path."
But aren't there paths that don't match up to menu items? Or are menu items in this content different things to begin with? And menu items containing functions? How do menu items contain functions?
Maybe The Definitive Guide is a confusing book and there are better resources for understanding how module development works? (I've searched the web for many resources already and they've all been just as confusing as Apress's)