There are two types of linking on a webpage absolute and relative. Relative linking is written in short and works within a website only. In absolute linking links are given in full url form. We can use this type of linking outside the website too.
Let me put it more simply for you. An absolute link is one which refers to some place as a complete url like www[dot]somesite[dot]com/filename.zip. Now the relative links are those which work relative to a site. For example if you are at a site www[dot]somesite[dot].com and refer to a page example.html on your main page in href that is a relative url. I hope i have explained your concern.