Abstract :
The modern smartphone is a masterpiece of adaptability. It lets you talk, snap photos, and tote around sprawling media collections. Downloadable apps let you do lots of other things, too, like track your workouts, monitor your diet, or remix a song. There???s even an app that helps you find hidden treasure, thanks to software that turns your device into a metal detector using the magnetic-field sensors that make up your smartphone???s compass.
