a GPS (Global Positioning System) receiver receives radio signals from a series of satellites orbiting the earth. It uses these to determine its position on the globe as well as altitude and time.
Waypoints and points of interes
A waypoint is the geographical coordinates (longitude, latitude and altitude) of a remarkable spot on an itinerary, defined by the users. Points of interest are those that have been built into the GPS system by the manufacturer.
a route is an itinerary mapped out in a GPS that you follow while hiking. You can map it out yourself on Internet or using mapping software or you can download one from a community website in a matter of 30 seconds.
Traces are a record of your journey. Each time you pass a waypoint, the GPS automatically records the time you passed it. These traces can be used to look back over the journey you took.