Final answer:
The electromagnetic spectrum categorizes different types of radiation from high-energy, shorter wavelength gamma rays to low-energy, longer wavelength radio waves, each with varying applications and implications for safety.
Step-by-step explanation:
The electromagnetic spectrum is a range of all types of EM radiation. Radiation is often categorized by its wavelength into several types. At one end of the spectrum are gamma rays, which have the highest frequencies and, correspondingly, the shortest wavelengths and highest energy. These include cosmic phenomena and radioactive decay. Gamma rays can be dangerous to biological systems. Next are X-rays, which are used in medical imaging but can also be harmful if exposure is excessive.
Moving lower in frequency we encounter ultraviolet rays, which can cause sunburn and is implicated in skin cancer but is also necessary for the production of vitamin D in humans. In the middle of the spectrum is visible light, which is the only portion of the spectrum that can be detected by the human eye. Infrared frequencies come after and are primarily associated with heat radiation.
Then we find microwaves, which are used in various technologies including microwave ovens and communications. Finally, at the lowest frequencies, are radio waves, which are used in broadcast technology among other applications. As frequency decreases, energy also decreases and the waves become safer for public exposure. Radio waves, with the lowest frequencies, are not harmful due to their low energy level and have applications ranging from broadcasting to radars.