In earlier times it was believed that sunlight (white light) was colourless. But Sir Isaac Newton (1643-1727) was the first person who suggested and then verified with his prism experiments that white light consists of a band of colours-VIBGYOR. He kept a prism in the sunlight such that light rays fell on one of the refracting surfaces of the prism. He also placed a screen near the other refracting surface and obtained a proper band of seven colours on the screen. From this experiment Newton concluded that white light consists of seven colours.