The flag of Uzbekistan dates from 1991, the year the country left the Soviet Union, and it was chosen to break with the Soviet design it replaced.
A flag chosen by competition, 1991
Uzbekistan declared independence from the Soviet Union on August 31, 1991, and adopted its flag on November 18 of the same year. The declaration took effect on September 1, which is the date the country marks as Independence Day. The design was picked through a national competition.
The flag it replaced was the flag of the Uzbek Soviet Socialist Republic, which used the hammer and sickle on red and blue and looked much like the other republican flags of the union. Across the former Soviet Union in those months, new governments were reaching for symbols that predated Moscow or had nothing to do with it at all, and Uzbekistan was doing the same thing.
Design and symbolism
Three horizontal stripes run blue, white and green, separated by two thin red lines. A white crescent moon and twelve white stars sit in the upper hoist corner.
Blue is the sky and clean water. White is peace and purity. Green is nature and fertility, and is usually tied to Uzbek farming.
The crescent is the standard symbol of Islam and stands for the country's religious inheritance, and also for its rebirth as an independent state after the Soviet period. The twelve stars are read two ways: as the twelve months of the Islamic lunar calendar, and as twelve regions of the country.
Where it flies
The flag hangs at government buildings and public institutions and is flown on national holidays, with set rules for raising and lowering it at state ceremonies. The military and some government bodies use variants that keep the same basic design and add their own insignia or lettering.
Schools make heavy use of it. Flag-raising and lessons on what the design means are a standard part of school ceremonies and cultural programs.
Shared imagery in Central Asia
The crescent puts Uzbekistan's flag in company with other flags in the region that draw on Islamic imagery, a legacy of the empires and cultures that shaped Central Asia over many centuries. The countries around it took very different routes to independence, but that visual vocabulary is common ground.
References
[1] Official Uzbekistan Government Website - Description of the national flag. (https://www.gov.uz/en)
[2] International Federation of Vexillological Associations - Publications on flag symbolism. (https://ifv.org)
[3] Historical records on Central Asian flags - Archival sources exploring the evolution of regional flags.
[4] Publications on post-Soviet state symbols - Analyzing transitions in national identities post-1991. (Various publications and journals on Central Asian studies)