A wearable computer is a small portable computer that is designed to be worn on the body during use. In this wearable computers differ from PDAs, which are designed for hand-held use. Wearable computers are usually either integrated into the user's clothing or can be attached to the body through some other means, like a wristband. They may also be integrated into everyday objects that are constantly worn on the body, like a wrist watch or a hands-free cell phone.
The aim of wearable computing community is to develop new user interfaces that augment non-computer activities, without interfering with the user's everyday tasks. The design of wearable computers is still a topic of research, and a variety of user interfaces is being proposed.
Some wearable computers use chorded keyboards and trackballs as input devices, but many try to use more intuitive means of input like gesture, speech recognition or context awareness. The output may be presented through displays, lights, sound or even haptic interfaces. Some augmented reality systems that can also be considered wearable computers.
Current experimental systems are often very large, sometimes even requiring the user to wear a backpack. It is assumed that such systems can be miniaturized some day, making it possible to embed them in clothing and accessoirs like glasses or watches. Some researcher hope that wearable computers will then become part of a networked ubiquitous computing environment.
Steve Mann's wearcomp has other properties such as operational constancy (the property that the computer is always on and ready for use).
The United States Army plans to issue 10,000 wearable computers to its combat troops in the next few years. They have approved a robust design that will supposedly be immune to weather, temperature, and vibration extremes. It consists of two belt-hung modules for power and processing, and an interface integrated with the regular combat helmet.