I can't really figure out what kind of programming PHP is. As far as I understand is it some sort of extra to the html code to make some dynamic things in the webpage. But some of my friends have also mentioned they were doing some programming in php. Does this mean they were making a webpage or what does it mean? I think it was some sort of program to organize clients online, so maybe it was some webpage.
Its just a programming language http://en.wikipedia.org/wiki/PHP yes, its very likely they were building a website.
PHP is good for Browser games, forums, social media sites of the sort...managing user accounts and storing it. I have been using it for years and find it easy to work with. Mixed with AJAX you can make some pretty cool things. It's all pretty much server-side and spits out the webpages in pure html.
HTML is just about your website's layout that how your webpages will look and show web content in browser while PHP is a programming language which performs back end functions in a website like when you click some button in a site and this performs some action so here a programming language is involve! New versions of html are dynamic to some extent!