Stated simply, a wearable computer is a computer that is always with you, is as comfortable as your own clothing, and is easy to carry and use. Steve Mann, a leader in wearable computer technology, is experimenting with personal area networks and taking convergence to a new level. Wearable computers have even sense what's going on around you.
Some wearables contain sensors that include wireless technology, cameras, or microphones.
For a detailed history of the evolution of computer-wear, see the MIT wearables timeline.