Classification of Electromagnetic Radiation
The electromagnetic radiation exists as a broad range of frequencies with their associated wavelengths and photon energies. These ranges of frequencies, wavelengths or photon energies are considered as the electromagnetic spectrum where different parts of it are called by different names. Among general names are radio waves, microwaves, infrared, visible light, ultraviolet, X-rays and gamma rays where in this list, from radio waves to gamma rays, frequencies and photon energies increase while wavelengths decrease. In other words, radio waves have the lowest frequencies and photon energies with the longest wavelengths among the other ones while gamma rays have the highest frequencies and photon energies beside the shortest wavelengths.
General characteristics of these different parts of electromagnetic spectrum like methods of their production, their interaction with matter and their practical applications vary from part to part. For example, photons of gamma rays, X-rays and high ultraviolet (ultraviolet with higher frequencies) can ionize atoms and molecules (provide the energy required to separate electrons from molecular entities) and therefore they are considered as ionizing radiation in contrast to nonionizing radiation name for electromagnetic radiations with lower frequencies and energies.
See above image for a more detailed classification of electromagnetic radiation. Abbreviations used in the above image are as follows:
EHF = extremely high frequency;
ELF = extremely low frequency;
HF = high frequency;
ITU = International Telecommunications Union;
LF = low frequency;
MF = medium frequency;
SHF = super high frequency;
SLF = super low frequency;
UHF = ultra-high frequency;
ULF = ultra-low frequency;
VHF = very high frequency;
VLF = very low frequency;