That big island is Forur I., you can see the west bound traffic moves in the deep shipping lane to the north, while the east bound traffic moves in the deep shipping lane to the south. Those deep water shipping lanes for the big maritime traffic is only 2 nautical miles wide in some places, so you can get a feel for why a big fight between Iran and anyone is a real bad thing for maritime traffic, they simply have no maneuver space and they have to pass within launch range of even small anti-ship missiles. It is a powerful strategic position, and no matter what anyone ever claims, in a war against Iran it would require Marines on that island to secure those shipping lanes.
That is also why China is building its blue water capacity, they know that when, not if, the US moves to alternative energy sources it will be China who has to keep those lines of communication at sea open. All of these things are interconnected, and often abused as fodder in militaristic rhetoric.
The Live Ship Map FAQ defines the purpose as thus:
This web site is created as an academic, open project. It is dedicated in providing free real-time information to the public, about ship movements and ports and our main objective is to expand it to other research applications. The project is currently hosted by the Department of Product and Systems Design Enginnering, University of the Aegean, Greece. The initial data collection is based on the Automatic Identification System (AIS). We are constantly looking for partners wishing to install an AIS receiver and share the data of their area with us, in order to cover more areas and ports around the world.More on the Automatic Identification System (AIS) can be found here, but this is the overview.
Picture a shipboard radar display, with overlaid electronic chart data, that includes a mark for every significant ship within radio range, each as desired with a velocity vector (indicating speed and heading). Each ship "mark" could reflect the actual size of the ship, with position to GPS or differential GPS accuracy. By "clicking" on a ship mark, you could learn the ship name, course and speed, classification, call sign, registration number, MMSI, and other information. Maneuvering information, closest point of approach (CPA), time to closest point of approach (TCPA) and other navigation information, more accurate and more timely than information available from an automatic radar plotting aid, could also be available. Display information previously available only to modern Vessel Traffic Service operations centers could now be available to every AIS-equipped ship.It is noteworthy that we track every airplane in the world, but we only track a small fraction of global commerce at sea, and yet 90% of global commerce moves at sea. Very cool tool, and a step towards Maritime Domain Awareness (PDF).
With this information, you could call any ship over VHF radiotelephone by name, rather than by "ship off my port bow" or some other imprecise means. Or you could dial it up directly using GMDSS equipment. Or you could send to the ship, or receive from it, short safety-related email messages.
The AIS is a shipboard broadcast system that acts like a transponder, operating in the VHF maritime band, that is capable of handling well over 4,500 reports per minute and updates as often as every two seconds. It uses Self-Organizing Time Division Multiple Access (SOTDMA) technology to meet this high broadcast rate and ensure reliable ship-to-ship operation.