Signal flags are colorful flags used in maritime communication to convey messages between ships or between a ship and the shore. Each flag represents a specific letter of the alphabet or a particular message, allowing sailors to communicate important information, such as navigational warnings or requests for assistance, without the need for radio or verbal communication. The International Code of Signals is a standardized system that defines the meanings of various signal flags. This system includes flags like the Alpha flag, which indicates a diver is in the water, and the Bravo flag, which signals that a ship is loading or unloading explosive materials.