In HTML when we provide link to internal pages using href (same is valid for other tags like img, form etc) we use relative/absolute path in the form of 'abc.jsp' or '/abc.jsp'
However we may want to switch the protocol (from HTTPS to HTTP for example) for the new link.
This is not possible without using complete URL ('http://mydomain/abc.jsp'). Using complete URL is not a good thing to do as the domain mane may vary and presence of proxies.
It is strange that HTML doesn't have a syntax for specifying the protocol for relative paths