The national flag of Indonesia, which is known as Sang Saka Merah-Putih (“The Sacred Red-and-White”) or Bendera Merah-Putih (“The Red-and-White Flag”) or simply Merah-Putih (“The Red-and-White”) in Indonesian, is based on the banner of the 13th century Majapahit Empire in East Java.

The Indonesian flag itself was introduced and hoisted in public at the Indonesian Independence Day ceremony, on 17 August 1945. The design of the flag has remained the same ever since.

The design of the Indonesian flag is simple with two equal horizontal bands, red (top) and white (bottom) with an overall ratio of 2:3. The flag is similar to the flag of Poland and flag of Singapore. The flag is identical to the flag of Hesse (a German state) and flag of Monaco, excluding the ratio. Red represents courage, while white represents purity of intent. Wikipedia