yin-yang - why is there a dot of the opposing colour within each colour?

In the Chinese symbol Tai Chi, or what is commonly recognized as the yin/yang symbol—the black and white complementary parts of one large and two small circles (originally the white color of the symbol was red) represents, as has already been suggested, that there is darkness in light and light in darkness. However, there is another interpretation concerning the the small circles where not only do they represent the reciprocal nature of light and darkness, but they also represent "the freedom to understand (become enlightened to) the significance of the reciprocal nature of reality--duality.

I'm not sure which is which, but either the black or the white is Yin or Yang. I think the dot is supposed to be the eye. And the only symbolic meaning of one without the dots, probably means the person was too lazy to finish the drawing.

South Korea's flag has a red/blue Yin Yang.

To show that there is darkness in light, and light in darkness :P

IDK about the second: maybe it signifies belief in the existence of pure good or evil, as opposed to the opposite being in each of us? or maybe it just looks cool?

bleh.

It's because contained within each color is the other color, it's just as simple as it seems. They aren't just equal to each other, but they contain each other.

every good contains some bad and every bad contains some good.

similarly to all polarities, such as man-woman