Alexander Graham Bell (March 3, 1847 – August 2, 1922) was a Scottish-Canadian-American scientist and inventor. Today, he is still widely considered to be the inventor of the telephone, although this matter has become controversial, with a number of people claiming that Antonio Meucci was the 'real' inventor and others holding out for Elisha Gray, the founder of the Western Electric Manufacturing Company. In addition to his work in telecommunications technology, he was responsible for important advances in aviation and hydrofoil technology.

Alexander Graham Bell was educated at the Royal High School of Edinburgh, from which he graduated at the age of 13. At the age of 16 he secured a position as a pupil-teacher of elocution and music in Weston House Academy, at Elgin, Moray, Scotland. The next year he spent at the University of Edinburgh.

From 1866 to 1867, he was an instructor at Somersetshire College at Bath, Somerset, England.

While still in Scotland he is said to have turned his attention to the science of acoustics, with a view to ameliorate the deafness of his mother.

In 1873, he accompanied his father to Montreal, Canada, where he was employed in teaching the system of visible speech. The elder Bell was invited to introduce the system into a large day-school for mutes at Boston, but he declined the post in favor of his son, who became Professor of Vocal Physiology and Elocution at Boston University's School of Oratory.

At Boston University he continued his research in the same field, and endeavored to produce a telephone which would not only send musical notes, but articulate speech. With financing from his American father-in-law, on March 7, 1876, the U.S. Patent Office granted him Patent Number 174,465 covering "the method of, and apparatus for, transmitting vocal or other sounds telegraphically ... by causing electrical undulations, similar in form to the vibrations of the air accompanying the said vocal or other sound", the telephone.

After obtaining the patent for the telephone, Bell continued his many experiments in communication, which culminated in the invention of the photophone-transmission of sound on a beam of light — a precursor of today's optical fiber systems. He also worked in medical research and invented techniques for teaching speech to the deaf. The range of Bell's inventive genius is represented only in part by the eighteen patents granted in his name alone and the twelve he shared with his collaborators. These included fourteen for the telephone and telegraph, four for the photophone, one for the phonograph, five for aerial vehicles, four for hydroairplanes, and two for a selenium cell.

Another of Bell's inventions was the photophone, a device enabling the transmission of sound over a beam of light, which he developed together with Charles Sumner Tainter. The device employed light-sensitive cells of crystalline selenium, which has the property that its electrical resistance varies inversely with the illumination (i.e., the resistance is higher when the material is in the dark, and lower when it is lighted). The basic principle was to modulate a beam of light directed at a receiver made of crystalline selenium, to which a telephone was attached. The modulation was done either by means of a vibrating mirror, or a rotating disk periodically obscuring the light beam.The photophone was patented on December 18, 1880, but the quality of communication remained poor and the research was not pursued by Bell.