Even during the short span of time that the Web has been in widespread use it has undergone a number of evolutionary changes - from addition of browser plug-ins and protocols such as Real Audio and Shockwave to development of languages and controls such as Java, JavaScript, and Active-X. More recently introduction of "push technologies" such as Castanet and Bongo by Marimba could transform the way that we conceptualize the Web. There are several consequences of this rapid evolutionary change.

Market pressures have resulted in proliferation of competing conceptual models. Vendors have realized that the key to success is to become the market standard through control of a widely adopted protocol. This realization fuels proliferation of competing sets of incompatible protocols in the hopes that one of them will win the evolutionary race.

The set of technologies popular at a given point in time is quite likely to have been replaced by a different model, concept, or feature set only a few months later. By one measure the beginning of the widespread popularity of hypermedia was signaled by the introduction of HyperCard in 1987. A decade later HyperCard is very nearly obsolete, as are many of the software tools introduced during the same era.

Software is rarely bug-free because software iterations occur so rapidly in response to competitive pressures as vendors strive for market share. The motto "We will sell no product before its time" no longer applies to the commercial software sector, if it ever did.

Despite the accelerating pace and instability in the information technology sector, there are some constants that can serve as points of stability in instructional programs. While HyperCard can no longer be considered state-of-the art by any standard, a modern-day Rip van Winkle who fell asleep ten years ago and awoke today would have no difficulty recognizing the heritage of HyperCard in Toolbook or Oracle Media Objects. Active-X and Bongo are more distantly related, but many elements of their graphical user interfaces reflect concepts originally embedded in HyperCard by Bill Atkinson.

The longest lasting dimension of a program of study in instructional technology is not memorization of the menus or command set of a particular application popular at a given point in time, but development of conceptual metaphors and cognitive maps representing the underlying abstractions. An understanding of style sheets in Microsoft Word facilitates understanding of stylesheets in Quark or Pagemaker, or the next generation of HTML standards. One goal of an instructional technology program is to provide exposure to a representative range of metaphors and conceptual models that will still be useful even as the technological infrastructure shifts. Appropriate cognitive maps, coupled with basic design principles, should stand the designer in good stead over the long haul.