Grandmothers are wearing Fitbit, Jawbone bracelets pack the shelves of big-box stores and Apple's smartwatch is expected to be one of the most coveted Christmas gifts this year. Wearable technology -- wireless-connected gadgets that come in the form of eyeglasses, bracelets, wristwatches and other small accessories for the body -- have gone from nerdy and outlandish devices to popular purchases for the average consumer, a sign of how comfortable we have become with tracking our daily activities, whether it's how well we sleep or how many calories we burn.