The Chinese symbols for "yin" and "yang" represent the duality of the universe as it is viewed in Taoism. The essence of existence in this view is opposites: male and female, dark and light, night and day. The symbols represent the simultaneous blending of these elements while they remain essentially apart. The yin-yang symbol is essentially a series of simple geometric shapes and curves that you can draw in a few steps using some simple techniques.
Draw a circle.
Divide the circle down the middle into two even halves.
Draw a circle on the center line with a diameter 1/2 the length of the center line. The top of this circle should touch the top line of the first circle.
Draw another circle of the same diameter beneath the first circle.
Erase the center line.
Draw a circle in the centers of the two smaller circles approximately 1/4 the diameter of the larger circles.
Fill in (darken) the lower of the two new circles.
Erase the left half of the larger upper circle.
Erase the right half of the larger lower circle.
Fill in (darken) the left swirl shape.