National flags, coat of arms, and crests grew out of heraldry used to identify nobility and royalty on the battlefield in European warfare. Having some kind of personal designation was important in this context, and because kings were associated with their personal heraldry, and also with the country, royal heraldry became associated with nations. In the age of exploration/sail having some kind of national flag became even more important, in order to identify friendly or enemy ships. The concept traveled with European colonialists.

Many national flags now extant have some symbolic connection to the flags of a parent nation, or a particular set of principles that inspired the founders of a nation. The French tricolor, for instance, replaced the Bourbon royal flag in 1794. It has since inspired "revolutionary" tricolor flags in numerous countries, including Italy and Mexico. Ethiopia, because of it's history of resisting colonialism, inspired the flag of several African countries with it's 3 color design. Britain's Union Jack is a merger of the flags of England and Scotland, and this has inspired the flags of loads of countries that were once part of the British Empire.