What is APRS and what can it do ?

APRS is an amateur radio based digital communications system for local, regional, or long-distance , real-time exchange of information among all members of a net, including map based displays for situational awareness. It was developed by Bob Bruninga (WB4APR).

APRS is used to transmit real-time information such as messages, bulletins, announcements and the locations of any stations or objects via amateur packet radio protocols. Real-time reporting of station position for mobiles is facilitated using the Global Positioning System.
APRS is capable of transmitting a wide variety of data including weather reports, short text messages, radio direction finding bearings, telemetry data, and storm forecasts. These reports can be combined with a computer and mapping software to show the transmitted data superimposed on a variety of map displays.