Signal flags, as a part of the International Code of Signals, can be used to communicate messages from one vessel to another while at sea. Signal flags employ an alpha-numeric code, which is the appropriate standard understood world wide.  Although mariners sometimes erroneously utilize nautical flags in combinations to dispatch a particular message, these signal flags are a more appropriate way to convey your important message. Most boaters string signal flags end-to-end and hang them from the rigging in bow-to-stern direction. Signal flags are also used to dress ships for ceremonial and festive occasions such as the beginning of the boating season.
The International Code of Signals has been in continuous use since 1857 when it was published by the British Board of Trade as a means of maritime communications. The original Code contained 17,000 signals using 18 signal flags, some of which were specific to the United Kingdom. The Code was revised in 1932 to include seven languages: English, French, German, Italian, Japanese, Spanish and Norwegian. When the code was revised again in 1969, the revision included Russian and Greek.