Wireless is a term used to describe telecommunications in which electromagnetic waves (rather than some form of wire) carrythe signal over part or all of the communication path. Some monitoring devices, such as intrusionalarms, employ acoustic waves at frequencies above the range of human hearing; these are also sometimes classified as wireless.


The first wireless transmitters went on the air in the early 20th centuryusing radiotelegraphy (Morse code). Later, as modulation made it possible to transmit voicesand music via wireless, the medium came to be called "radio." With theadvent of television, fax, data communication, andthe effective use of a larger portion of the spectrum, the term "wireless" hasbeen resurrected.