Videotelephony (also known as videoconferencing or video calling or telepresense) is the use of audio and video for simultaneous two-way communication. Today, videotelephony is widespread. There are many terms to refer to videotelephony. Videophones are standalone devices for video calling (compare Telephone). In the present day, devices like smartphones and computers are capable of video calling, reducing the demand for separate videophones. Videoconferencing implies group communication. Videoconferencing is used in telepresence, whose goal is to create the illusion that remote participants are in the same room.
The concept of videotelephony was conceived in the late 19th century, and versions were demonstrated to the public starting in the 1930s. In April, 1930, reporters gathered at AT&T corporate headquarters on Broadway in New York City for the first public demonstration of two-way video telephony. The event linked the headquarters building with a Bell laboratories building on West Street.Early demonstrations were installed at booths in post offices and shown at various world expositions. AT&T demonstrated Picturephone at the 1964 World’s Fair in New York City. In 1970, AT&T launched Picturephone as the first commercial personal videotelephone system. In addition to videophones, there existed image phones which exchanged still images between units every few seconds over conventional telephone lines. The development of advanced video codecs, more powerful CPUs, and high-bandwidth Internet service in the late 1990s allowed digital videophones to provide high-quality low-cost color service between users almost any place in the world.
