Wireless is a term used to describe telecommunications in which electromagnetic waves (rather than some form of wire) carry the signal over part or all the communication path. Some monitoring devices, such as intrusion alarms, 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 century using radiotelegraphy (Morse code). Later, as modulation made it possible to transmit voices and music via wireless, the medium had become called "radio." With the advent of television, fax, data communication, and the effective use of a larger portion of the spectrum, the term "wireless" has been resurrected.

Common examples of wireless equipment in use today include:

•    Cellular phones and pagers -- provide connectivity for portable and mobile applications, both personal and business

•    Global Positioning System (GPS) -- allows drivers of vehicles, captains of boats and ships, and pilots of aircraft to ascertain their location anywhere on earth

•    Cordless computer peripherals -- the cordless mouse is a common example; keyboards and printers can be linked to a computer via wireless

•    Cordless telephone sets -- these are limited-range devices, not to be confused with cell phones

•    Home-entertainment-system control boxes -- the VCR control and the TV channel control are the commonest examples; some hi-fi sound systems and FM broadcast receivers also use this technology

•    Remote garage-door openers -- among the oldest wireless devices in common use by consumers; usually operates at radio frequencies

Wireless technology is rapidly evolving, and is playing an increasing role in the lives of people internationally. In addition, ever-larger numbers of people are relying on the technology directly or indirectly. (It has been suggested that wireless is overused in some situations, creating a social nuisance Wireless can be divided into:

•    Fixed wireless -- the operation of wireless devices or systems in homes and offices, and in particular, equipment attached to the Internet via specialized modems

•    Mobile wireless -- using wireless devices or systems aboard motorized, moving vehicles; examples include the automotive cell phone and PCS (personal communications services)

•    Portable wireless -- the operation of autonomous, battery-powered wireless devices or systems outside the office, home, or vehicle; examples include handheld cell phones and PCS units

•    IR wireless -- the application of devices that convey data via IR (infrared) radiation; employed in certain limited-range communications and control systems.