A wearable system to monitor, measure, and train walking The system is made of an extremely user-friendly app, a smartphone, and three small wireless sensors. Gait Tutor acts as a virtual coach: it evaluates in real-time the quality of gait and guides the person with clear vocal messages to walk safely, effectively and smoothly. Gait Tutor is a Medical Device developed for promoting a healthy and active lifestyle, to delay the natural functional decline. The system is made of an extremely user- friendly APP, a smartphone, and three small wireless sensors. Gait Tutor acts as a virtual coach: evaluates in real-time the quality of gait and guides the person with clear vocal messages to walk safely, effectively and smoothly. Moreover, Gait Tutor is a clinical research tool able both to show in real time gait events and to log hours of outdoor walking providing extremely accurate stepby-step spatio-temporal gait parameters and posture information.