A wearable computer is a computer that is subsumed into the personal space of the user, controlled by the user, and has both operational and interactional constancy, i.e. is always on and always accessible. Most notably, it is a device that is always with the user, and into which the user can always enter commands and execute a set of such entered commands, and in which the user can do so while walking around or doing other activities". 
The first person to pioneer the idea of being able to compute anywhere and be connected was Steven Mann, the inventor of Wearable computing. He thought that humans should not contort to computers, but that computers should contort to humans. He wore 80 pounds of computing equipment, including a wireless uplink to an early manifestation of the Internet (MIT's local Internet) starting in 1979. As time progressed, computing became lighter, and Steve Mann’s load became less burdensome while still retaining the same functionality. Similarly, computers have jumped from gymnasiums to desktops to pockets.
Steve Mann envisioned a future in which hardware could be downloaded in as easily as software. Where one’s contact lens prescription could change during the day based on one’s needs. A future where a device morphs is the most fluid and liquid that an interface can become. Interfaces today are limited by their external structure. This limitation will dissolve when the hardware dissolves.
WearCam: The Wearable Camera
Dr. Mann's WearComp invention dates back to his high school days in the 1970s and early 1980s, where he was experimenting with wearable computing and personal imaging as a personal hobby . "Unlike other wearable devices (wristwatches, regular eyeglasses, wearable radios, etc.), a WearComp is as reconfigurable as the familiar desktop or mainframe computer. Unlike other computers (including laptops and PDAs), a WearComp is inextricably intertwined with its wearer - WearComp's "always ready" characteristic leads to a new form of synergy between human and computer".
Modern Wearable Computing
Although the Internet is invisible and seemingly omnipresent, it is only accessible by two-dimensional interfaces on physical machines in connected fields. It has only been a recent occurrence that we’ve been able to carry around complex computational interfaces in our pockets, increasing technological capabilities into our everyday lives. Until this point, one had to be in a certain time and place in order to access computing power. This usually meant a college or university, and sometimes between the hours of 3 and 6 Am.
Steve Mann's Formal Definition of Wearable Computing
Operational modes of wearable computing
There are three operational modes in this new interaction between human and computer.
The computer runs continuously, and is always ready to interact with the user. Unlike a hand-held device, laptop computer, or PDA, it does not need to be opened up and turned on prior to use. The signal flow from human to computer, and computer to human runs continuously to provide a constant user interface.
Traditional computing paradigms are based on the notion that computing is the primary task. Wearable computing, however, is based on the notion that computing is NOT the primary task. The assumption of wearable computing is that the user will be doing something else at the same time as doing the computing. Thus the computer should serve to augment the intellect, or augment the senses.
Unlike hand held devices, laptop computers, and PDAs, the wearable computer can encapsulate us (Fig. 1c). It doesn't necessarily need to completely enclose us, but the concept allows for a greater degree of encapsulation than traditional portable computers. There are two aspects to this encapsulation:
It can function as an information filter, and allow us to block out material we might not wish to experience, whether it be offensive advertising, or simply a desire to replace existing media with different media. In less severe manifestations, it may simply allow us to alter our perception of reality in a very mild sort of way.
Mediation allows us to block or modify information leaving our encapsulated space. In the same way that ordinary clothing prevents others from seeing our naked bodies, the wearable computer may, for example, serve as an intermediary for interacting with untrusted systems, such as third party digital anonymous cash "cyberwallets".
Six Attributes (Signal Paths) of Wearable Computing
There are six informational flow paths associated with this new human-machine synergy. These signal flow paths are, in fact, attributes of wearable computing, and are described, in what follows, from the human's point of view:
Unmonopolizing of the user's attention
(The Wearable Computer) does not cut you off from the outside world like a virtual reality game or the like. You can attend to other matters while using the apparatus. It is built with the assumption that computing will be a secondary activity, rather than a primary focus of attention. In fact, ideally, it will provide enhanced sensory capabilities. It may, however, mediate (augment, alter, or deliberately diminish) the sensory capabilities.
Unrestrictive to the user
Is ambulatory, mobile, roving; "you can do other things while using it". E.g. you can type while jogging, etc.
Observable by the user
Can get your attention continuously if you want it to; within reasonable limits (e.g. that you might not see the screen while you blink or look away momentarily) the output medium is constantly perceptible by the wearer.
Controllable by the user
The system must be controllable by the user in the idea that one can grab control of it anytime they wish and can be used as a communication medium when you want it to.
Attentive to the environment
It is environmentally aware, multimodal, multisensory. (this ultimately increases the user's situational awareness). Communicative to others: it can be used as a communications medium when you want it to.
It allows the wearer to be expressive through the medium, whether as a direct communications medium to others, or as means of assisting the production of expressive media (artistic or otherwise).
Allows the wearer to be expressive through the medium, whether as a direct communications medium to others, or as means of assisting the production of expressive media (artistic or otherwise).
Implied by the above six properties is that it must also be:
Always on, running, and ready. May have "sleep modes" but is never "dead" (unlike a laptop computer, which must be opened up, switched on, and booted up before use).
human and computer are inextricably intertwined.
You can adapt to it so that it acts as a true extension of mind and body; after time you forget that you are wearing it.
Resists, if you wish, prohibition or requests by others for removal. This is in contrast to a laptop, in briefcase or bag, that could be separated from you by the "please leave all bags and briefcases at the counter" policy of a department store, library, or similar establishment.
Others can't observe or control it unless you let them.
Future of Wearable Computing
The whole of the Internet is an invisible, 4th dimensional potentiality with portals of different sizes, shapes, and capabilities. The hardware determines the size of the portal, the connection determines the rate of information flow, and the software/web browser and the sites within that web browser determine the rate of information absorption into the mind. The rate of information absorption is dependant upon the format of the information presented. Wearable Computers will evaporate over time until they are no longer noticeable or are proper ubiquitous extensions of the self, as valuable and as iconic as sports cars and external transport structures for the physical body. Their interfaces will be invisible.
- Wearcomp.org Definition of Wearcomp.
- EyeTap.org Glossary entry on Wearcomp
- Adapted from Steve Mann's address [Wearable Computing as Means for Personal Empowerment http://www.eyetap.org/wearcam/icwc98/keynote.html] Keynote Address for The First International Conference on Wearable Computing, ICWC-98, May 12-13, Fairfax, VA. Originally found at EyeTap Glossary