Die Hypertextidee entstand bereits 1945, d. h. kurz nach der Erfindung des Computers, aber noch vor dem Bau des ENIAC. Sie wird in der Regel zurückgeführt auf einen Aufsatz des damaligen wissenschaftlichen Beraters von Präsident Roosevelt, Vannevar Bush. In diesem Aufsatz, der 1945 in der Zeitschrift The Atlantic Monthly erschien, warnt Bush vor einer bevorstehenden Informationsexplosion und arbeitet einen Lösungsvorschlag aus. Dabei stellt er seine neue Idee dem bisher üblichen Erschließungs- und Retrieval-Verfahren, dem Indexieren, gegenüber:
Our ineptitude in getting at the record is largely caused by the artificiality of systems of indexing. When data of any sort are placed in storage, they are filed alphabetically or numerically, and information is found (when it is) by tracing it down from subclass to subclass. It can be in only one place, unless duplicates are used; one has to have rules as to which path will locate it, and the rules are cumbersome. Having found one item, moreover, one has to emerge from the system and re-enter on a new path. The human mind does not work that way. It operates by association. With one item in its grasp, it snaps instantly to the next that is suggested by the association of thoughts, in accordance with some intricate web of trails carried by the cells of the brain. It has other characteristics, of course; trails that are not frequently followed are prone to fade, items are not fully permanent, memory is transitory. Yet the speed of action, the intricacy of trails, the detail of mental pictures, is awe-inspiring beyond all else in nature. Man cannot hope fully to duplicate this mental process artificially, but he certainly ought to be able to learn from it. In minor ways he may even improve, for his records have relative permanency. The first idea, however, to be drawn from the analogy concerns selection. Selection by association, rather than by indexing, may yet be mechanized. One cannot hope thus to equal the speed and flexibility with which the mind follows an associative trail, but it should be possible to beat the mind decisively in regard to the permanence and clarity of the items resurrected from storage. Consider a future device for individual use, which is a sort of mechanized private file and library. It needs a name, and to coin one at random, "memex" will do. A memex is a device in which an individual stores all his books, records, and communications, and which is mechanized so that it may be consulted with exceeding speed and flexibility. It is an enlarged intimate supplement to his memory (Bush URL 1).
Bush dachte dabei nicht an einen Computer, sondern stellte sich vor, daß ein derartiges Gerät auf Mikrofilm und Photozellen beruhen würde. Wichtig ist aber, daß mit Memex genau das verwirklicht werden sollte, was heute als Hypertext bezeichnet wird:
"...the basic idea of which [associative indexing] is a provision whereby any item may be caused at will to select immediately and automatically another. This is the essential feature of the memex. The process of tying two items together is the important thing" (Bush URL 2).