Below-the-fold Definition

(newspapers) Referring to a photograph, headline, or article printed on the lower half of the front page of a broadsheet newspaper, such that it is not immediately visible on a folded copy of the newspaper, e.g. as displayed at a newsstand or in a vending machine.

(by extension, web design) Referring to that portion of a web page which is far enough down that it is not likely to be visible in the initial display of a standard browser window, such that the reader will probably have to scroll down before seeing it.