The web server stores all its documents in a directory tree

rooted at some configured directory, known as its "document

root". Normally the URI part of the URL (the part after

the hostname) is used as a relative path from the document

root to the desired file or directory. A redirect directive

allows the server administrator to specify exceptions to this

general mapping from URL to file name by telling the browser

"try this URL instead". The new URL may be on the same server

or a different one and may itself be subject to redirection.