Red is always at the top of the arc. The easiest way to remember the sequence of all rainbows' colors is to remember the nemonic device, Mr. Roy G. Biv:
R – red
O – orange
Y – Yellow
G – green
B – blue
I – Indigo
V - violet
Red is the first recognizable color of a rainbow, followed by orange, yellow, green, blue and purple. There are actually millions of colors in a rainbow, some not visible to the naked eye.
