Your browser downloads these onto your computer and then reads the HTML document which tells it where to put the text and pictures on your screen. If you then click on a link to another web site, the browser reads the address of that link from the HTML document and calls up the computer where the other sites files are stored, and so on. This can be a bit confusing because the term has come to mean many things. It can mean the default page that comes up when you launch you web browser. Smileys are little faces turned sideways, turn your head to the left.
Great minds think alike.