As you can see from the image above, red has the longest wavelengths and violet has the shortest. An easy way to remember these colors is ROY-G-BIV (red, orange, yellow, green, blue, indigo, violet).
The speed of light in a vacuum is defined to be 299,792,458 m/s (or about 186,282 miles per second). All forms of electromagnetic radiation move at exactly this same speed in vacuum.
The study of light and the interaction of light and matter is called optics. The observation and study of optical phenomena such as rainbows and the aurora borealis offer clues as to the nature of light.