Signal flags provide a way to communicate information relating to safety, distress, medical, and operational information, especially when language difficulties arise says marine flags international guard. Each signal flag has a unique and complete meaning.
 

 

Single letter signals are used for urgent and important issues, or issues of very common use. Two-letter and three-letter signals are used for other messages.
 

Strung from the forward waterline over the bow to the masthead, then over the stern to the aft waterline, signal flags are also used to dress ship for holidays or special occasions.