I have seen some servers have default page icon for each pages without having to add using html. example:
and even the site in which we are i.e
on this sites the html code <link href="url" rel="icon" type="type"/> is not used yet they have icon set for each page can you please tell me how it is done.
It's not related to .htaccess (or PHP). Browsers automatically request a /favicon.ico file when loading a page. Wikipedia and Google can tell you more.