Electromagnetic waves are waves generated by the electromagnetic energy, that depends on the oscillation or acceleration of an electric charge.
These waves travel through space at the speed of life; the strength id waves varies, with alternating crests and troughs.
The distance between positive and negative crests is called amplitude, while the distance between two consecutive crests is called wavelenght.
The number of waves in a second is called frequency.
The radiation of electromagnetic waves forms a spectrum, that extends from high frequency to low frequency; the spectrum consists of gamma rays, x-rays, ultraviolet radiation, infrared radiation and radio waves.
Every kind of waves has different purposes; for example radio waves are used in television broadcasting, the telephone transmission, radar, ect.
Infrared rays are used in some industrial processes, while ultraviolet rays are used as disinfectant.
X-rays and gamma rays help to diagnose disorders in the body and to trat cancer.
With the development of the laser in the 1960s, it's also possible to transmit messages and voice through infrared rays.