Although Wi Fi surround the enviroments as a energy field, it’s not visible to a eye. It is shared radio channel and each computer listen the channel. Cell phones,televisions and radios also do use the radio waves. However their (the waves) unique height, power (amplitude), distance from each other, and their travelling speed give them a clean transmission that cannot interrupted by other signals. For example, they are longer than microwaves and shorter than radio waves. Wifi routers are antenna. Their ability is sending the data over multiple frequencies all at the same time.
Radio frequency energy is part of the electromagnetic spectrum that includes visible light and x rays. Heinrich Hertz is a German physicist discovered radio waves in 1888 by providing the existence of electromagnetic waves theorized by James Clerk Maxwell’s electromagnetic theory of light.