Nobody picks a flag's colors at random. Red dominates in Algeria and Afghanistan; the Bahamas and Belize lean on blue. Those choices carry emotional weight, and the weight is not the same everywhere.
Why color choice matters in flag design
Colors influence how people feel about what they are looking at, which is why designers argue about them. Red tends to read as passion, power and vitality. Blue reads as calm, stability and trust. Green and yellow suggest nature, growth and optimism. Nations pick from that vocabulary to say something about themselves, and the picks stick around for centuries.
Red
Red carries energy, bravery and resilience. Algeria and Afghanistan both put it front and center.
In both cases the red stands for courage and sacrifice. On China's flag it means something else: revolution and unity.
Canada's red points at sacrifice too, along with historical ties.
Blue
Blue reads quieter. The Bahamas and Belize both use it for peace and trust.
Ukraine's blue is the sky and freedom. Argentina's is the sky and hope. Same color, different arguments.
Yellow and green
Yellow, on the flags of Brazil and Germany, usually signals wealth and energy.
Green pulls toward nature and hope, as it does on the flags of Mexico and Libya.
Both colors tend to soften the more intense hues they sit beside.
The same color does not mean the same thing
Color associations are cultural, not universal. In Japan white stands for purity and truth. In much of the West it reads as peace, or as surrender. Historical events and local tradition do most of the work, which is why reading a flag by color alone will mislead you as often as it helps.
