In the UK, the APRS frequency is 144.800 while the US uses 144.390.  APRS packets are transmitted for all other stations to hear and use. Packet repeaters, called digipeaters, then store and retransmit packets. All stations operate on the same radio frequency, and packets move from digipeater to digipeater. All stations within radio range of each digipeater receive the packet. At each digipeater, the packet path is changed. The packet will be repeated through only a certain number of digipeaters depending upon what 'PATH' setting is configured.  Digipeaters keep track of the packets they forward for a period of time, thus preventing duplicate packets from being retransmitted. This keeps packets from circulating in endless loops around the network. Eventually, most packets are heard by an APRS Internet Gateway, called an IGate, and the packets are routed on to the Internet APRS backbone (where duplicate packets heard by other IGates are discarded) for display or analysis by other users connected to an APRS-IS server, or on a web site designed for the purpose.  APRS stations can be seen on a map at https://aprs.fi