previously generated and new information; and capabilities surpassing those of humans for seeing, hearing, and speaking (see Box 1.2). The integration of such specific advances into applications and systems that are more complex than today's state of the art can only be speculated on. What is not speculation is the fact that today 's society depends greatly on IT, and tomorrow's will do so even more. The Internet of today is a beginning, not an end point: it may be thought of as infrastructure, but it is far from offering the stability and predictability associated with the traditional infrastructures of the physical world.
IT research takes many forms. It consists of both theoretical and experimental work, and it combines elements of science and engineering. Some IT research lays out principles or constraints that apply to all computing and communications systems; examples include theorems that show the limitations of computation (what can and cannot be computed by a digital computer within a reasonable time) or the fundamental limits on capacities of communications channels. Other research investigates different classes of IT systems, such as user interfaces, the Web, or electronic mail (e-mail). Still other research deals with issues of broad applicability driven by specific needs. For example, today 's high-level programming languages (such as Java and C) were made possible by research that uncovered techniques for converting the high-level statements into machine code for execution on a computer. The design of the languages themselves is a research topic: how best to capture a programmer's intentions in a way that can be converted to efficient machine code. Efforts to solve this problem, as is often the case in IT research, will require invention and design as well as the classical scientific techniques of analysis and measurement. The same is true of efforts to develop specific and practical modulation and coding algorithms that approach the fundamental limits of communication on some channels. The rise of digital communication, associated with computer technology, has led to the irreversible melding of what were once the separate fields of communications and computers, with data forming an increasing share of what is being transmitted over the digitally modulated fiber-optic cables spanning the nation and the world.
Experimental work plays an important role in IT research. One modality of research is the design experiment, in which a new technique is proposed, a provisional design is posited, and a research prototype is built in order to evaluate the strengths and weaknesses of the design.