Deep linking
Deep Linking is a policy invented by the press, and quite possibly by "linking policies" that some sites have established.
A hyperlink that links to a specific file within a website is considered a deep link. It started I think when sites began to complain that their advertisements were circumvented by deep linking. Other sites such as The Wall Street Journal charge for "permenant" links, and many critics charge that many sites simply want to establish policies that will "license" such links to the highest bidder. They argue that links are a fundamental part of "user-oriented" web browsing.
Some sites may not have the cash to deal with search boxes or affilfiate programs they may have once had. Some sites may resist frames (as some sites use it to brand other people's content.) This is not deep linking but it is part of the fundamental problem: sites cannot exist or are not happy without their advertising dollars.
The Press: http://www.ala.org/alaorg/oif/deeplinking.html (this is a deep link-- to avoid deep-linking, I would go to www.ala.org.) Google: "deep linking"