Pick almost any color and a cluster of national flags will be built around it, often for very different reasons. Red shows up more than any other color worldwide, tied to revolution in some countries and to sacrifice or bloodshed in others. Green leans heavily toward Islam and toward agriculture and fertility. Blue often points to water, sky, or peace. None of these associations are universal though, which is part of what makes comparing them interesting: the same color can mean nearly opposite things depending on where you look.
This page groups every national flag by its dominant color, so you can see how far a single shade travels, and how differently it gets used along the way.
Flags with Red
The most common color in flag design worldwide, carrying revolution in one country and sacrifice in the next.
Blue Flags
Water, sky, and peace, the recurring themes behind the world’s blue flags.
Green Flags
Islam, agriculture, and the forests and fields a country is built on.
Yellow Flags
Gold, sun, and mineral wealth, rarely a flag’s only color but often its boldest.
Black Flags
Rare as a dominant color, and almost always deliberate when it appears.
White Flags
Peace and purity, the most common secondary color even when it isn’t the star.