[pixxa]

Most Desktop web browsers provide quite many affordances for links, and do so automatically upon hover: change cursor, underline, pop up link description, show URL in status area.

Touch UIs can't have these "introspective" affordances because hover is not practical in a touch-based UI.

Even with all these affordances, if a Web UI didn't distinguish a link from other content visually, it would make for a difficult interface to traverse.

[king_jester]

Very much this, hyperlinks are visually distinct elements in pure HTML and get color and style change (underline) to indicate the link. One of my biggest pet peeves are sites that alter link style in CSS so that it loses those kinds of visual clues and makes it harder to know what can or cannot be clicked.