The first person to split white light into spectral colors with a prism was Italian priest Francesco Maria Grimaldi, in 1665. Isaac Newton introduced the term color spectrum in his "New Theory about Light and Colors," which was published in 1672 and described experiments conducted in 1666.
Newton's experiments were designed to disprove a then-popular theory that light was a wave and the spectrum emitted by a prism was caused by the prism corrupting or coloring the wave. Newton believed that light was made up of colored particles that combined to form white. He proved this by using two prisms in succession to split and then recombine white light. Newton also named the seven colors constituting the spectrum: red, orange, yellow, green, blue, indigo and violet.