CAUTION

 News URLs like mailto URLs, might not be supported by all browsers.

FILE

File URLs are intended to reference files contained on the local disk. In other words, they refer to files located on the same system as the browser. For local files, file URLs take one of these two forms: the first with an empty hostname (three slashes rather than tow ) or with the hostname as locaslhost:

File://dir1/dir2/file

File://localhost/dir1/dir2/file

Depending on your browser, one or the other will usually work. (if you’re in doubt, you can open the file from within your browser and look at the address bar to see what its file:URL is.)

File URLs are very similar to FTP URLs. In fact, if the host part of a file. URL is not empty or local host. You browser will try to find the given file by using FTP.both of the following URLs result  in the same file being loaded in the same way.

File://somesystem.com/pub/dir/foo/file.html

Ftp://somesystem.com/pub/dir/foo/file.html

Probably the best use of file URLs is in startup pages for your browser (which are also called home pages.). in this instance, because you’ll almost always be referring to a local file, using a file RUL makes sense.

The problem with file URLs is that they f\reference local files, where local means on the same system as the browser pointing to the file-not the same system from which the page was retrieved! If you use file URLs as links in your page, and someone from elsewhere on the internet encounters your page and tries to follow those links, that person’s browser will attempt to find the file on her local disk (and generally will fail). Also, because file URLs use the absolute pathname to the file, if you use file URLs in your page, you can’t move that page elsewhere on the system or to another system.

If your intention is to refer to files that are on the same file system or directory as the current page, use relative pathnames rather than file URLs. With relative pathnames for local files and other URLs for remote files, you shouldn’t need to use a file URL at all