Myanmar's flag is barely more than a decade old. It was adopted on October 21, 2010, replacing the socialist-era design that had flown since 1974, and the switch came as the country moved from military rule towards a more civilian administration in the run-up to that year's general elections.
The flags before 2010
The previous flag had a red field with a blue canton holding 14 stars arranged around a cogwheel and a rice plant, industry and agriculture in the usual socialist shorthand. During British rule the territory flew the Union Flag. After independence in 1948, Burma, as it was then called, used a red field with a blue canton bearing a single large white star.
Three stripes and a star
Three horizontal stripes run yellow, green, and red from top to bottom, with a large white five-pointed star centered across all of them. Yellow stands for solidarity, green for peace and tranquility, and red for courage and decisiveness. The star is the union itself.
How the flag is flown
Government institutions fly it and it appears at national events. Protocol says it must not touch the ground, and it should be flown above all other flags except those of other countries. Different government bodies, the military among them, use variants marked for their own branch while keeping the central star.
References
[1] International Federation of Vexillological Associations, Records and Descriptions of Flags