<P> Wireless communication, or sometimes simply wireless, is the transfer of information or power between two or more points that are not connected by an electrical conductor . The most common wireless technologies use radio waves . With radio waves distances can be short, such as a few meters for Bluetooth or as far as millions of kilometers for deep - space radio communications . It encompasses various types of fixed, mobile, and portable applications, including two - way radios, cellular telephones, personal digital assistants (PDAs), and wireless networking . Other examples of applications of radio wireless technology include GPS units, garage door openers, wireless computer mice, keyboards and headsets, headphones, radio receivers, satellite television, broadcast television and cordless telephones . </P> <P> Somewhat less common methods of achieving wireless communications include the use of other electromagnetic wireless technologies, such as light, magnetic, or electric fields or the use of sound . The term wireless has been used twice in communications history, with slightly different meaning . It was initially used from about 1890 for the first radio transmitting and receiving technology, as in wireless telegraphy, until the new word radio replaced it around 1920 . The term was revived in the 1980s and 1990s mainly to distinguish digital devices that communicate without wires, such as the examples listed in the previous paragraph, from those that require wires or cables . This became its primary usage in the 2000s, due to the advent of technologies such as LTE, LTE - Advanced, Wi - Fi and Bluetooth . </P> <P> Wireless operations permit services, such as long - range communications, that are impossible or impractical to implement with the use of wires . The term is commonly used in the telecommunications industry to refer to telecommunications systems (e.g. radio transmitters and receivers, remote controls, etc .) which use some form of energy (e.g. radio waves, acoustic energy,) to transfer information without the use of wires . Information is transferred in this manner over both short and long distances . </P> <P> The world's first wireless telephone conversation occurred in 1880, when Alexander Graham Bell and Charles Sumner Tainter invented and patented the photophone, a telephone that conducted audio conversations wirelessly over modulated light beams (which are narrow projections of electromagnetic waves). In that distant era, when utilities did not yet exist to provide electricity and lasers had not even been imagined in science fiction, there were no practical applications for their invention, which was highly limited by the availability of both sunlight and good weather . Similar to free - space optical communication, the photophone also required a clear line of sight between its transmitter and its receiver . It would be several decades before the photophone's principles found their first practical applications in military communications and later in fiber - optic communications . </P>

What do data signals on a wireless communication system travel on