The Electromagnetic Spectrum is the entire range of electromagnetic radiation extending in frequency from zero Hertz to 1023 cycles per second (or Hertz).[1]
Longer wavelengths of electromagnetic radiation such as used in AM radio have lower frequencies (540 to 1600 KHz). FM radio has much shorter wavelengths and higher frequencies (88 to 108 MHz).
Even higher frequencies give as microwave radiation, used in radar and cooking. Still higher is infrared (which can keep food warm from a lamp or heat up your skin from sunlight or fire). Infrared is used in "black light" photography.
Next highest in frequency (and lower in wavelengths) is visible light: red, orange, yellow, green, blue, indigo and violet.
Ultraviolet light can give you a suntan (or burn), and too much of certain UV frequencies can increase one's risk of skin cancer. Some frequencies are blocked by the Earth's ozone layer.
Even higher frequencies include X-rays and gamma rays.