Absolute vs relative URLs

Question

I would like to know the differences between these two types of URLs: relative URLs (for pictures, CSS files, JS files, etc.) and absolute URLs.

In addition, which o

Answer 1

A URL that starts with the URL scheme and scheme specific part (http://, https://, ftp://, etc.) is an absolute URL.

Any other URL is a relative URL and needs a base URL the relative URL is resolved from (and thus depend on) that is the URL of the resource the reference is used in if not declared otherwise.

Take a look at RFC 2396 – Appendix C for examples of resolving relative URLs.