AC power  -   · "Alternating current." This type of electrical power system, attributed to George Westinghouse, had the power to transmit voltages of up to 1000V. The key to this power was the transformer, which reduced high voltages to safe levels. AC power became a serious competitor with Edison's DC power because it could transmit over greater distances at lower costs, although detractors claimed it was unsafe.

DC power  -   · "Direct current." This was Edison's preferred form of electrical power system. Though it could only transmit voltages up to 240V, it had many advantages in the battle for electrical dominance. Edison's generators were more advanced and his systems could transmit power as well as electricity.

Gold & Stock  -   · This New York City telegraph company provided the young Edison with his first jobs and invention contracts. Their primary customer was the Stock Exchange. In 1870 they commissioned Edison to create a printer and a telegraph, facsimiles of the most advanced types, for them.

Kinetoscope -   · Edison invented this technology for viewing projection films in 1891. Though he could have used it as a projection device, he decided that he could make more money using it as a peepshow device. Hence, the Nickelodeon, built for one person to view a film at a time.

Menlo Park -   · Edison's first research laboratory was established in Menlo Park, New Jersey in 1876. Edison's most creative and successful period as an inventor was spent here. The laboratory itself, with its emphasis on a loose hierarchy, cooperation, innovation and teamwork, became the model for many science and technology research laboratories afterwards.

Nickelodeon -   · These individual viewing devices, powered by Edison's Kinetoscopes, were incredibly popular with urban audiences in the 1890s. For twenty-five cents admission, customers entered parlors of the machines and passed along them, viewing short films.

Ore-milling -   · This is widely considered as Edison's most disastrous foray into industrial production. Throughout the 1880s and 1890s he sunk the majority of his personal fortune into an elaborate ore-milling production designed to transform the production of iron and steel for furnaces. The process involved concentrating magnetic iron ore, magnetite, into small briquettes.

patent -   · Patents were an integral part of an inventor's life, and Edison owned over 1,000 of them by the end of his life. They were licenses given to an inventor by the federal government to forbid others from copying or stealing the invention.

phonograph -   · One of Edison's most famous inventions, although it was not until another inventor threatened to bring it to market that he paid attention to it seriously as a consumer product. Edison and a team of researchers invented it at Menlo Park in November 1877, partially using telephone technology.

Storage battery -   · One of Edison's later (pre-World War One) preoccupations was the creation of a storage battery that would serve as a source of power for consumers and businesses. Many inventors had unsuccessfully attempted to create a safe, effective, commercially successful storage battery for some fifty years before Edison took up the challenge in the early 1900s. He joined their ranks, despite making headway in the field.

telegraph -   · The telegraph, first completed in 1837 by two Englishmen, transformed communication in the United States during the first half of the nineteenth century. (In fact, transcontinental telegraphy preceded transcontinental railroads by seven years.) As a young man, Edison was fascinated with both the telegraph and the life of a telegrapher, and many of his first inventions revolve around the device.

telephone -   · Although the work for the telephone belongs to several inventors, the modern, practical telephone is generally credited to Alexander Graham Bell, who patented his device in March 1876. Edison quickly moved to improve upon Bell's invention.

Thomas Edison, Inc. -   · On March two, 1911, all of Edison's many companies were incorporated into the greater body of Thomas Edison, Inc. The move represents a greater move towards the philosophy of big business.

West Orange -   · The second of Edison's great research facilities, established in 1886 in West Orange, New Jersey. This laboratory was much larger than the one at Menlo Park and less romantic, though Edison accomplished much here, including work on the electric lighting system and the phonograph and invention of the motion picture camera and the dictating machine.

Western Union -   · The major telegraphing company in America by the 1870s, it bought Gold and Stock and multiple small telegraphing companies in the late 1860s. Edison worked in many of their offices during his youth.

Alexander Graham Bell  -  Bell, chiefly known as a teacher for the hearing-impaired, was working on a harmonic telegraph when he stumbled on telephone principles. He later became one of Edison's chief rivals for control of the telephone and the phonograph on the commercial marketplace.

Charles Edison - The son of Edison and Mina, he took over Thomas Edison, Inc., upon his father's retirement. He was the company's director until 1957, when it was sold to McGraw Electric Company.

George Westinghouse  -  The chief proponent of the AC power system in the 1880s. He battled Edison for control of the market for decades. By the 1920s it became clear that his system had triumphed, after the invention of a rotary converter by a former Edison employee made flexibility in electric power delivery possible.

Henry Ford  -  Not just the inventor of the Model T car and the owner of an incredible automobile industry, Ford was also a production innovator and a good friend of Edison in the 1910s. Ford once said that Edison was one of the "three greatest inventors of this age."

Joseph Swan  -  An English inventor who performed much of the background work on electrical lighting technology before Edison picked up the hunt for an electrical light system in the 1870s and 1880s. When Edison came out with his electrical lighting system, Swan responded with a lawsuit.

Mary Stilwell - Edison's first wife. They were married on Christmas Day, 1871, when Mary was sixteen. They had three children by 1878. Mary was shy and frequently placed under stress by the demands of her husband's absences. She died at the age of twenty-nine, in 1884.

Mina Miller - Edison's second wife. They were married on February twenty-four, 1886, when she was nineteen. A woman of strong religious conviction and independent personality, she was a constant companion to Edison during his later years. They had three children.