MIT Technology Review 
July 5, 2013
Many of us already record the places we go and things we do by using our smartphone to diligently snap photos and videos, and to update social media accounts. A company called ARO  is building technology that automatically collects a more comprehensive, automatic record of your life.
ARO is behind an app called Saga  that automatically records every place that a person goes. Now ARO’s engineers are testing ways to use the barometer, cameras, and microphones in a device, along with a phone’s location sensors, to figure out where someone is and what they are up to. That approach should debut in the Saga app in late summer or early fall.
The current version of Saga, available for Apple and Android phones, automatically logs the places a person visits; it can also collect data on daily activity from other services, including the exercise-tracking apps FitBit and RunKeeper, and can pull in updates from social media accounts like Facebook, Instagram, and Twitter. Once the app has been running on a person’s phone for a little while, it produces infographics about his or her life; for example, charting the variation in times when they leave for work in the morning.
Software running on ARO’s servers creates and maintains a model of each user’s typical movements. Those models power Saga’s life-summarizing features, and help the app to track a person all day without requiring sensors to be always on, which would burn too much battery life.