Depends were your file is. If its in the same folder then you can use a relative path and link to just the file name file.php. If the file is in another folder then to link to it you’d say folder/file.php. If you need to come out of a folder and then back into the folder were the file is you’d say. …/folder/file.php. Or you can say start from the root (not the folder) by saying /folder/file.php.
The safest (and easiest way) is to provide a path relative to the root folder. That way, the same path works no matter where it’s placed in the site. If you want a link to the jQeury file on each page, for example, this is the way to go.
So let’s say you have a folder in your site’s root folder (where your home page is) called /scripts/, and in there is your jQuery library script, jquery.min.js or whatever. You can link to that file from anywhere in your site with:
The only caveat is that these root relative links (with the slash at the front) don’t work on your desktop version, unless you have a virtual server environment set up.