Before it starts, Trailprint shows a disclosure. After you continue and allow location access, RME records precise GPS points, timestamps and accuracy to reveal your route and calculate distance, area and streaks. Recording stays on in the background, even with the phone locked or RME closed, until you tap Stop revealing. Stopping ends new collection but does not erase saved history.
Trailprint is separate from Friends Map’s active-location sharing. Who sees your exact route is a setting: Private (only your account), Friends (mutual friends) or Public (signed-in RME members on your profile).

