Apache Reference: http_core, DocumentRoot

DocumentRoot

Root Directory of Document Tree
Syntax: DocumentRoot A
Example: DocumentRoot /home/www
Since: Apache 1.0

This directive sets the directory from which Apache, by default, will serve documents. Unless matched by a directive like Alias or Rewrite==Rule, the server appends the path from the requested URL to the directory argument to create a path to the document. To accommodate internal Apache logic, you should avoid trailing slashes in directory.