What Makes A Great Flag

For some reason I've always liked the Japanese flag. So now I sit here wondering what makes a good flag. After doing some research this is what I found out.1.A flag should be simple enough for a young child to draw and not have a complicated coat of arms like the Mexican flag.2.It should have meaningful designs but they should still be simple.3.It should have effective use of colour but not to much (about three colours is recommended).Now that I think about it the Japanese flag has all of these. It is a simple but effective red circle on a white background. It is also represents the sun rising through the sky so that ticks box number two. Finally it contains only two colours red and white which complement each other nicely. I also like the South Korean flag as well which also happens to tick all these boxes.