What means "Links can be either absolute or relative."?

Answer 1

A link is an absolute link if the URL and file name can be found from anywhere on the Web, not just from a narrow location. ... A relative link specifies the name of the file to be linked to only as it is related to the current document. so the path to that would be restricted compared to absolute.

Answer 2

Ok, MR.Peter, thank you very much!
I figured this out.