The flag of Palestine is a tricolor of three equal horizontal stripes (black, white, and green from top to bottom) overlaid by a red triangle issuing from the hoist. This flag is derived from the Pan-Arab colors and is used to represent the State of Palestine and the Palestinian people. It was first adopted on 28 May 1964 by the PLO. The flag day is celebrated on 30 September.
The flag is almost identical to that of the extinct Hashemite Kingdom of Hejaz and to that of Ba'ath Party.
Wikipedia page: Flag of Palestine