What is green white and black flag with red triangle?

There are several flags with green, white, black, and red triangle, so it's important to specify which one is being referred to.

One flag that matches this description is the flag of the Arab Democratic Republic of Sahara, also known as the Sahrawi Arab Democratic Republic. The flag features a horizontal tricolor of green, white, and black, with a red triangle on the hoist side. The red triangle includes a black star and crescent, which is commonly associated with Islam.

The flag was adopted in 1976, when the Sahrawi Arab Democratic Republic declared independence from Spain and claimed control over the disputed territory of Western Sahara. The green, white, and black stripes represent pan-Arab colors, with green symbolizing the fertile lands of the region, white representing peace, and black representing the dark past of colonialism and oppression. The red triangle with the star and crescent is a nod to the Islamic faith, which is the predominant religion in the region.

Overall, the green, white, black, and red triangle flag is a symbol of the Sahrawi people's struggle for independence in Western Sahara, as well as their Arab and Islamic identity.