Absolute vs relative vs "slash" URL? - url

Question

If this full URL:
http://domain.com/dir/file.css
Is an "absolute URL", where the link will work from any website.
And this:
../dir/file.css
Is a "relative URL", where the link will only work from that directory path.
What is the combination of those two called…
/dir/file.css
Where the link will work from any location on that site?

Answer 1

Your first example is a URL. Your second and third examples are not URLs, they're paths. If the path begins with / then it's an absolute path, otherwise it's a relative path.
Web browsers generally understand how to interpret a path in relation to the "current" host and path.

Answer 2

You’re basically talking about a URI scheme. In your example:
/dir/file.css
This is considered the path:
/dir/
And this is the filename:
file.css
So saying “hostname plist path & filename” is a safe bet. Or perhaps /dir/file.css can be considered the root path since the / at the beginning anchors it to the hostname part of the URL.
This diagram from Wikipedia explains it well:
foo://username:password#example.com:8042/over/there/index.dtb?type=animal&name=narwhal#nose
\_/ \_______________/ \_________/ \__/ \___/ \_/ \______________________/ \__/
| | | | | | | |
| userinfo hostname port | | query fragment
| \________________________________/\_____________|____|/ \__/ \__/
| | | | | | |
| | | | | | |
scheme authority path | | interpretable as keys
name \_______________________________________________|____|/ \____/ \_____/
| | | | | |
| hierarchical part | | interpretable as values
| | |
| path interpretable as filename |
| ___________|____________ |
/ \ / \ |
urn:example:animal:ferret:nose interpretable as extension
path
_________|________
scheme / \
name userinfo hostname query
_|__ ___|__ ____|____ _____|_____
/ \ / \ / \ / \
mailto:username#example.com?subject=Topic