Although we are particularly sensitive to visible light, electromagnetic waves cover a huge range of frequencies. We split them up into several main types, depending on their frequency and on how they are produced. As you move down the list below the energy and frequency decrease, and the wavelength increases.

• gamma rays are produced by radioactive decays and nuclear decays.
  
  
• X-rays are produced by decelerating electrons.
  
  
• ultraviolet (UV), visible, and infrared (IR) waves are produced by electron transitions and by vibrating atoms and molecules.
  
  
• microwaves and radio and TV waves are produced by charges accelerated in antennas.
  
  
• waves with even lower energy are known as long waves, because of their very long wavelength

Electromagnetic waves can have a number of different interactions with the human body, including:

• Gamma rays and X-rays are known as ionizing radiation. They can cause chemical changes as well as mutations of DNA.
  
  
• Ultraviolet light is associated with suntans, sunburns, and cataracts.
  
  
• Rods and cones in our eyes are sensitive to visible light, which is why we can see.
  
  
• Heat sensors in our skin can detect infrared waves.
  
  
• We're not particularly sensitive to anything with a longer wavelength.