The flag of Serbia is a tricolour with Pan-Slavic colours, with three equal horizontal fields, red on the top, blue in the middle and white on the bottom. The same tricolour, in a number of variations, was the flag of Serbia throughout history, and is the National flag of Serbs. On the State flag there is a small Coat of arms of Serbia centered vertically and located left of center by one-seventh of the flag's length.

A similar flag was also used between 1882, when Serbia was proclaimed a kingdom, and abandoned in 1918, when it joined the Kingdom of Serbs, Croats and Slovenes. In 1945, Serbia became a republic within the Socialist Federal Republic of Yugoslavia and a communist star was added to the middle, was officially dropped in 1992. The current form of the flag was officially adopted on August 16, 2004 in form of recommendation issued by the Parliament of Serbia. By adoption of the new Constitution of Serbia on November 8 2006, its usage became constitutionally sanctioned (along with the coat of arms and anthem), and the state and national (popular) flag were equalized. The version without the Coat of arms was used as the State and the National (civil) flag, and since continued to be used as a National Flag only.

From: Wikipedia.org