A flag is a piece of cloth hung from a pole for signalling (as in semaphore) or to identify the bearer, in this sense also called a standard. A national flag is one of the important official symbols of a nation or country. The study of flags is known as vexillology.
Some particularly famous or interesting flags are:
- The Union Flag (often incorrectly referred to as the "Union Jack"), the flag of the United Kingdom.
- The Dannebrog, the national flag of Denmark. Also the similar Nordic-cross flags of the other Nordic countries.
- The Stars and Stripes, the national flag of the United States.
- The Flag of Russia (horizontal tricolour of white, blue and red), the source for the Panslavic colours adopted by many Slavic states and peoples for their national flag.
- The Ethiopian flag (horizontal triband of green, yellow and red), the source for the Panafrican colours adopted by many African countries for their national flag.
Subdivisions of countries frequently have flags. Government agencies and educational or other private institutions also sometimes have flags. The United Nations has a flag. The European Union also has a flag (see European flag).
A great many specialized flags are used to signal between ships or from ship to harbour in ship transport. An example is an entirely yellow flag, which means that the ship's crew is quarantined for an infectious disease.
See also: Gallery of flags, List of flags, Flag Terminology