I don't have an iphone, so have always wondered about thee kind of 'apps', so without seeming too thick, can someone explain?

the iphone has a browser, and most sites have mobile versions, or are more and more being designed with these in mind (a case of point being the recent disasterous relaunch of the bbc news site itself). So what exactly does an 'app' do in these cases?

if I'm reading it right, they replace flash content with something that an apple product can use?

if this is so, why can't we (900/810/800) users access these sites/streams/whatever that the 'app' is accessing?

hopefully this isn't too obvious and someone will respond in the spirit of the question!