The Singaporean Flag

Singapura

Two equal horizontal bands of red (top) and white; near the hoist side of the red band, there is a vertical, white crescent (closed portion is toward the hoist side) partially enclosing five white five-pointed stars arranged in a circle; red denotes brotherhood and equality; white signifies purity and virtue; the waxing crescent moon symbolizes a young nation on the ascendancy; the five stars represent the nation's ideals of democracy, peace, progress, justice, and equality. (Source) 

The name of the flag is Singapura. It was adopted on 3 December 1959, when Singapore gained self-governance from the British Empire. When Singapore gained full independence on 9 August 1965, it was reconfirmed as the national flag.


The predecessors flags are:

The flag of the Straits Settlements (together with Malacca and Penang). The Straits Settlement Flag is made up of a British Blue Ensign with three gold crowns (one each for the 3 settlements) in a red inverted pall (inverted Y), used between 1874 and 1942.

From 1946 to 1959, i.e. from shortly after the Second World War until the granting of self-governance, Singapore was an independent Crown colony and had its own flag. It was adapted from the Straits Settlements flag by reducing the number of crowns to one, representing Singapore.

(Source)