Automatic Identification System (AIS) is a new technical system that makes it possible to monitor ships from other ships, and from shore based stations. AIS will become a requirement. See the International standardisation section. AIS equipped ships will continuously transmit a short message containing information of position, course over ground (COG), speed over ground (SOG), gyro course (heading), etc. Ships equipped with AIS meeting anywhere on earth will be able to identify and track each other without being dependent of shore stations. Shore stations will also get the same information from ‘AIS-ships’ within the VHF area of the station when monitoring the coastal areas and the ports. The AIS is using a broadcast and an interrogating self organised technology, the so called AIS STDMA/ITDMA, that operates ship-to-ship and ship-to-shore including limited communication capabilities. AIS does not require a radar. This article will stress the advantages of the AIS, show how to use it and why the techniques can operate and handle the information from all ships even in the most dense shipping waters of the world