Niger adopted its flag on November 23, 1959, when the Territorial Assembly approved the design, some eight months before the country became independent of France on August 3, 1960. Until then French colonial symbols were the only ones flying, and the republic in waiting wanted something of its own. The design has not changed since.
The stripes and the disc
Three horizontal bands, orange, white, and green from top to bottom, with an orange circle at the center of the white one.
Orange is the Sahara, which covers much of northern Niger and sets the terms for life there. White is peace and purity, which in a region that has seen a great deal of conflict reads more as intent than as description. Green is hope and the fertile land of the Niger River valley, where the country's farming happens. The circle is usually taken as the sun, and sometimes as independence and the unity of the Nigerien people.
Flying it
Government buildings and state institutions fly the flag, and it appears at official events and diplomatic functions. Independence Day on August 3 brings it out in parades and public ceremonies. There are no official variants, though stylized versions turn up for cultural and promotional purposes.
Related flags
Horizontal tricolors are common across West Africa, a product of the same wave of decolonization and of pan-African influence. Côte d'Ivoire, next door, uses orange and green as well, though its flag runs vertically and has no central symbol.
References
Presidency of Niger Official Documentation
International Federation of Vexillological Associations