From: http://www.maxi-pedia.com/what%20is%20DFS

What is DFS you ask today. DFS stands for Distributed File System and is a technology in the Microsoft 
shop related to sharing files across networks, specifically across wide area networks.

From: http://www.maxi-pedia.com/what%20is%20DFS%20root%20how%20to%20create%20DFS%20root

DFS root is the starting point of the DFS namespace. DFS root is an object which consolidates 
your network shared folders and makes them available to network users as a single entry point.

From: http://msdn.microsoft.com/en-us/library/cc771058.aspx

To use DFS Replication, you must create replication groups and add replicated folders to the groups.

From: http://technet.microsoft.com/en-us/library/cc732863(v=ws.10).aspx

To install DFS if the file server role has already been added
Click Start, point to All Programs, point to Administrative Tools, and then click 
Server Manager. In the console tree of Server Manager, right-click the Files Services 
node, and then click Add Role Services. Follow the steps in the Add Roles Services Wizard, 
and supply the information described in the following table.