Transmission is a physical characteristic value that stands for the permeability of media. The term transmission occurs in radio technology and in optical transmission components, in optics, acoustics, medicine, mechanical engineering, thermodynamics and in many other disciplines.
In the context of IT knowledge, transmission or transmissivity is about the permeability of media and the behavior of radio waves, light waves, and sound waves in relation to reflection and absorption. If a wave hits a medium, then depending on the nature of the medium and the wave, part of the wave can be reflected, absorbed and transmitted.
Reflection is the portion of the wave energy that is reflected back from the medium, absorption is the portion that is absorbed by the medium, and transmission is the portion that passes through the medium. The ratio between the energy after and before the medium is the transmittance.