The flag of Serbia is a tricolour consisting of three equal horizontal bands, red on the top, blue in the middle and white on the bottom. The same tricolour, in some variations, was the flag of Serbia throughout its history, and is the ethnic flag of the Serbian people. The current form of the flag was officially adopted on November 11, 2010.

The state flag bears the lesser coat of arms, centered vertically and shifted to the hoist side by one-seventh of the flag's length. The flag ratio is 2:3 (height/width), with three equal horizontal bands of red, blue and white, each taking one third of the height. Recommended colours are:

The oldest known description of a flag of Serbia is from the 1281 description of a flag in the treasury of Stephen Vladislav I of Serbia (1233–1243), which was kept in the Republic of Ragusa. The description lists "vexillum unum de zendato rubeo et blavo" - a flag of fabric red and blue (zendato - čenda a type of light, silky fabric). A flag design usually seen in commemorations of medieval events have this horizontal diband. As Vladislav ruled from 1233 to 1243 and died after 1264, the flag predates the time of the description, and as it was found in royal treasury it's possible to have been used even earlier.

Serbia ⁱ/ˈsɜrbiə/, officially the Republic of Serbia (Serbian: Република Србија / Republika Srbija, pronounced [rɛpǔblika sř̩bija]), is a landlocked country located at the crossroads of Central and Southeast Europe, covering the southern part of the Carpathian basin and the central part of the Balkans. Serbia borders Hungary to the north; Romania and Bulgaria to the east; the Republic of Macedonia to the south; and Croatia, Bosnia and Herzegovina, and Montenegro to the west; additionally, it borders Albania through Kosovo, whose status as part of Serbia is disputed. Serbia covers an area of 88,361 km² and has a population of just over 7.1 million, while the capital and largest city is Belgrade.

The arrival of the Serbs to the Balkans in the 7th century, established several states, eventually forming the Serbian Empire in the 14th century. By the 16th century, Serbia was conquered and occupied by the Ottoman Empire, at times interrupted by the Habsburgs. In the early 19th century the Serbian revolution re-established the country as the region's first constitutional monarchy, which subsequently expanded its territory and pioneered the abolition of feudalism in the Balkans. The former Habsburg crownland of Vojvodina united with Serbia in 1918. Following World War I, Serbia formed Yugoslavia with other South Slavic peoples which existed in several forms up until 2006, when the National Assembly of Serbia declared independence and the legal succession to the former State Union. In February 2008 the parliament of UNMIK-governed Kosovo, Serbia's southern province, declared independence, with mixed responses from international governments.