Flag of South Vietnam

The flag of South Vietnam was designed by Emperor Thành Thái in 1890 and was revived by Emperor Bảo Đại in 1948. It was the flag of the former State of Vietnam (the French-controlled areas in both Northern and Southern Vietnam) from 1949 to 1955 and later of the Republic of Vietnam (South Vietnam) from 1955 until April 30, 1975 when the south unconditionally surrendered to the north, to which it was officially joined in a unified Vietnam a year later. The flag consists of a yellow field and three horizontal red stripes and can be explained as either symbolising the unifying blood running through northern, central, and southern Vietnam, or as representing the symbol for "south" (as in, south from China (Viet Nam itself) and also 'nam' meaning south), in Daoist trigrams.

It is still used by many Vietnamese emigrants now living in other countries, mainly because the current Vietnamese flag is considered to be offensive to them, as it's the flag of the current Communist regime - the regime most Overseas Vietnamese (Viet Kieu) fled from in the late 1970s and 1980s as Boat People. From February 2003 to August 2006, in the United States, 13 states, seven counties and 85 cities have adopted resolutions recognizing the yellow flag as the "Vietnamese Heritage and Freedom Flag".