The Automatic Identification System (AIS) is an automatic tracking system used on ships for identifying and locating vessels by electronically exchanging data with other nearby ships, AIS base stations, and satellites (S-AIS).

Information provided by AIS equipment, such as unique identification, position, course and speed can be displayed on a screen and is intended to assist vessel officers and also allow authorities to track and monitor vessel movements.

The International Maritime Organization‘s International Convention for the Safety of Life at Sea requires AIS to be fitted aboard international voyaging ships with gross tonnage (GT) of 300 or more which includes all seismic vessels.

Further information can be found here https://en.wikipedia.org/wiki/Automatic_Identification_System