One of the most popular uses of a flag is to symbolize a nation or country. Some national flags have been particularly inspirational to other nations, countries, or subnational entities in the design of their own flags. Some prominent examples include:

* The flag of Denmark is the oldest state flag still in use (dates back to the 13th century). This flag, called the Dannebrog, inspired the cross design of the other Nordic countries: Norway, Sweden, Finland, Iceland, and regional Scandinavian flags for the Faroe Islands, Åland, Scania and Bornholm, as well as flags for the non-Scandinavian Shetland and Orkney. * The Tricolour of the Netherlands is the oldest tricolor, first appearing in 1572 as the Prince's Flag in orange–white–blue. Soon the more famous red–white–blue began appearing—it is however unknown why, though many stories are known. After 1630 the red–white–blue was the most commonly seen flag. The Dutch Tricolor has inspired[citation needed] many flags but most notably those of Russia, New York City, and South Africa (the 1928–94 flag). * The national flag of France, the Tricolore was designed in 1794. As a forerunner of revolution, France's tricolour flag style has been adopted by other nations. Examples: Italy, Costa Rica, Dominican Republic, Ireland, Haiti, Romania, Mexico, etc. * The flag of Russia, the source for the Pan-Slavic colors red, white and blue, adopted by many Slavic states and peoples as their symbols. Examples: Slovakia, Serbia, Croatia, and Slovenia. * The Union Flag (Union Jack) of the United Kingdom is the most commonly used. British colonies typically flew a flag based on one of the ensigns based on this flag, and many former colonies have retained the design to acknowledge their cultural history. Examples: Australia, Fiji, New Zealand, Tuvalu, and also the Canadian provinces of Manitoba, Ontario and British Columbia, and the American state of Hawaii; see commons:Flags based on British ensigns. * The flag of the United States, also nicknamed The Stars and Stripes or Old Glory. In the same way that nations looked to France for inspiration, many countries were also inspired by the American Revolution, which they felt was symbolized in this flag. Examples: Liberia, Chile, Malaysia, Uruguay, and the French region of Brittany. * The original tricolor Flag of Iran, the source for the Pan-Iranian colors Green, White and Red adopted by many Indo-Iranian or Aryan states and peoples as their symbols. Examples: Tajikistan, Kurdistan, Republic of Ararat, Talysh-Mughan. * Ethiopia was seen as a model by emerging African states of the 1950s and 1960s, as it was one of the oldest independent states in Africa. Accordingly, its flag became the source of the Pan-African colors, or "Rasta colors". Examples: Togo, Senegal, Ghana, Mali. * The flag of Turkey, which is very similar to last flag of the old Ottoman Empire, has been an inspiration for the flag designs of many other Muslim nations. During the time of the Ottomans the crescent began to be associated with Islam and this is reflected on the flags of Algeria, Azerbaijan, Comoros, Malaysia, Mauritania, Pakistan and of Tunisia. * The Pan-Arab colors, green, white, red and black, are derived from the flag of the Great Arab Revolt as seen on the flags of Jordan, Kuwait, Sudan, Syria, the United Arab Emirates, Western Sahara, Egypt, Iraq, Yemen and Palestine. * The Soviet flag, with its golden symbols of the hammer and sickle on a red field, was an inspiration to flags of other communist states, such as East Germany, People's Republic of China, Vietnam, Angola, Afghanistan and Mozambique. * The flag of Venezuela, created by Francisco de Miranda to represent the independence movement in Venezuela that later gave birth to the "Gran Colombia", inspired the flags of Colombia and Ecuador, both sharing three bands of yellow, blue and red with the flag of Venezuela. * The flag of Argentina, created by Manuel Belgrano during the war of independence, was the inspiration for the United Provinces of Central America's flag, which in turn was the origin for the flags of Guatemala, Honduras, El Salvador, and Nicaragua.

National flag designs are often used to signify nationality in other forms, such as flag patches.