#Request pipeline
Applies to: Umbraco 6.0+
This section explains how Umbraco builds its URLs and how the URLs are mapped back to nodes
##Introduction
The request pipeline was rewritten by Stéphane Gay and explained at "Codegarden 13" on 2013/06/13. This documentation is based on the slides which he made public using this tweet.
##What is the pipeline The request pipeline is the process of building up the URL for a node, resolving a request to a specified node and making sure that the right content is sent back.
Stéphane make it pretty clear with a very basic image:
##Outbound vs Inbound The pipeline works bidirectional: inbound and outbound.
Outbound is the process of building up a URL for a requested node. Inbound is every request received by the web server and handled by Umbraco.
##Works by default You don't need to do anything for the pipeline to work. However, if you want to adapt it to your needs, you will need knowledge of the following topics: