The flag of Serbia is a red, blue, and white tricolor with the national coat of arms set into it. Both parts have long histories, and both have been rearranged more than once.
From medieval crosses to the Pan-Slavic tricolor
Serbian states in the Middle Ages flew flags carrying crosses and other Christian symbols drawn from the Orthodox faith. Under Ottoman rule Serbia had no official flag, though regional symbols survived in various territories.
As Serbia won autonomy and then independence in the 19th century, it needed a national flag. The Pan-Slavic movement and the colors of the French Revolution both fed into the choice, and a red, blue, and white tricolor was adopted in the 1830s. It was formalized when the Kingdom of Serbia was proclaimed in 1882.
The modern version dates from November 11, 2010. It keeps the tricolor and adds the national coat of arms, which had itself been reworked repeatedly through the Yugoslav era and again when modern Serbia took shape in the early 2000s.
The tricolor and the double-headed eagle
Three horizontal stripes, red, blue, and white, in a pattern used across the Slavic nations. Red stands for the struggle for freedom and for sacrifice, blue for the sky and for hope, white for peace and purity.
The coat of arms carries a double-headed eagle and a royal crown. The eagle points to Byzantine influence on Serbian culture, the crown to the historical monarchy.
Usage
The flag is displayed at government buildings, official ceremonies, and national holidays, and at international events where Serbia is represented. It should never touch the ground, must be illuminated if flown at night, and must be in good condition.
Military and civic organizations use their own versions, adding symbols relevant to each institution while keeping the core design.
The flag has a long association with public protest in Serbia as well as with celebration, which is part of why it carries the weight it does.
Similar flags and influences
Serbia's flag resembles those of Russia, Slovenia, and Croatia, all of which use the Pan-Slavic colors. The Russian tricolor is the most direct influence, reflecting historical ties between the two countries. The double-headed eagle comes from a different lineage, linking Serbia to Byzantine and Eastern Orthodox tradition.