A walkie-talkie is a hand-held, portable, two-way radio
Two-way radio
A two-way radio is a radio that can both transmit and receive , unlike a broadcast receiver which only receives content. The term refers to a personal radio transceiver that allows the operator to have a two-way conversation with other similar radios operating on the same radio frequency...

A transceiver is a device comprising both a transmitter and a receiver which are combined and share common circuitry or a single housing. When no circuitry is common between transmit and receive functions, the device is a transmitter-receiver. The term originated in the early 1920s...

. Its development during the Second World War has been variously credited to Donald L. Hings, radio engineer Alfred J. Gross
Alfred J. Gross
Alfred J. Gross , a.k.a. Irving J. Gross was a pioneer in mobile wireless communication. He created and patented many communications devices, specifically in relation to an early version of the walkie-talkie, Citizens' Band radio, the telephone pager and the cordless telephone...

, and engineering teams at Motorola
Motorola, Inc. was an American multinational telecommunications company based in Schaumburg, Illinois, which was eventually divided into two independent public companies, Motorola Mobility and Motorola Solutions on January 4, 2011, after losing $4.3 billion from 2007 to 2009...

. Similar designs were created for other armed forces, and after the war, walkie-talkies spread to public safety and eventually commercial and jobsite work. Major characteristics include a half-duplex
Duplex (telecommunications)
A duplex communication system is a system composed of two connected parties or devices that can communicate with one another in both directions. The term multiplexing is used when describing communication between more than two parties or devices....

 channel (only one radio transmits at a time, though any number can listen) and a "push-to-talk" (PTT) switch that starts transmission
Transmission (telecommunications)
Transmission, in telecommunications, is the process of sending, propagating and receiving an analogue or digital information signal over a physical point-to-point or point-to-multipoint transmission medium, either wired, optical fiber or wireless...