Vietnamese women in ao dai. Photo from Tranhgaorang.com
In some regions married women wear bright and colorful ao dai, unmarried girls – dresses of pastel colors, and young girls – white ao dai. It's their everyday clothes, in which they go to work or school. But in another parts of the country women wear light brown short shirts and long black skirts in everyday life.
Actually, ao dai wasn't the first national dress in Vietnam. The earliest version (since 12th century) was Ao tu than, which used to be rather popular centuries ago. Later it evolved into the early ao dai which had five flaps: one under the front lap, two in the back, and two in the front. Ao tu than wasn't so tight-fitted and had a lower collar.