Page manager is a critical tool for Drupal development. It's a sub-module of Chaos Tools that enables you to change the paths of pages, even some of those defined by Drupal core. While it won't change the appearance of a node, it can change the context of it. With Page Manager you can control who has access to pages, and how they get to the pages, including nodes that are part of other pages. Working hand-in-hand with other modules like Panels, Page Manager can help give you great control over the user experience.
Drupalize.Me and NodeOne have a series of free video lessons on working with this powerful module...
1.) Overview of the Page Manager Module
2.) Node Page Overrides, Contexts & Page Redirects
3.) Variants and Selection Rules
4.) Introduction to Panels