how many colors in a rainbow

A rainbow commonly has seven colors: red, orange, yellow, green, blue, indigo, and violet. This traditional sequence is often remembered by the mnemonic "ROYGBIV." The conception of seven colors in a rainbow goes back to Isaac Newton's division of the visible spectrum, although some modern interpretations may merge indigo into blue or violet, viewing the number of distinct colors as somewhat arbitrary. However, the classic and widely taught view is that a rainbow consists of these seven colors in that order, from red on the outside to violet on the inside.