Wearable technologies will help advance precision medicine by allowing clinically relevant parameters describing an individual's health state to be measured. The development of a wide range of wearable technologies that can be modified for use in healthcare has been fueled by the lifestyle and fitness markets. Wearable technology will help advance precision medicine by allowing for the measurement of high-information-content, clinically-relevant indicators. Wearable technology has exploded in popularity in the lifestyle and fitness industries, with accelerometer-based activity monitors and photoplethysmography-based heart monitors among the most widely available gadgets. Wearables are part of the mobile health sector, which also includes a variety of customized apps. Despite the rapid development of devices in the leisure and fitness markets, wearable sensors have had a sluggish entry into the healthcare business.