Bell Laboratories (also known as Bell Labs and formerly known as AT&T Bell Laboratories and Bell Telephone Laboratories) was the main research and development arm of the United States Bell System. At its peak, Bell Labs was the premier facility of its type, developing a wide range of revolutionary technologies, including the transistor, laser, information theory, the UNIX operating system, and the C programming language. There have been 6 Nobel Prizes awarded for work done at Bell Labs. 
Bell Labs had research and development facilities throughout the USA, with the greatest concentration of facilities located in New Jersey. Among the locations in New Jersey were Crawford Hill, Freehold, Holmdel, Lincroft, Long Branch, Middletown, Murray Hill, Piscataway, Red Bank and Whippany. The largest facility in the country was in Illinois, at Naperville-Lisle, which had the single largest concentration of employees (about 11,000) prior to the telecomm bust of 2000. There were also facilities in Columbus, Ohio, Allentown and Breinigsville in Pennsylvania, and Westminster, Colorado. Since 2000, many of the former Bell Labs locations have been scaled back or shut down entirely.
Bell Telephone Laboratories Inc. was established 1925 by Walter Gifford (then president of AT&T) as a separate entity which would take over the work being conducted by Western Electric's engineering department's research division. Ownership of Bell Labs was evenly split between AT&T and Western Electric.
During its first year of operation, Facsimile (fax) transmission was first demonstrated publicly by the Bell Labs. In 1926, the laboratories invented the first synchronous-sound motion picture system , and continued to produce inventions throughout its lifetime.
In 1927, a long-distance television transmission of images of Herbert Hoover from Washington to New York was successful, and in 1928 the thermal noise in a resistor was first measured by John B. Johnson with Harry Nyquist, who provided a theoretical analysis. During the 1920s, the one-time pad cipher was invented by Gilbert Vernam and Joseph Mauborgne at the labs; Bell's Claude Shannon later proved that it was unbreakable.
In 1933, a foundation for radio astronomy was laid by Karl Jansky during his work investigating the origins of static on long-distance communications. He discovered that radio waves were being emitted from the center of the galaxy. Also in 1933, stereo signals were transmitted live from Philadelphia to Washington DC. In 1937, the vocoder, the first electronic speech synthesizer was invented and demonstrated by Homer Dudley. Bell researcher Clinton Davisson shared the Nobel Prize in Physics with George Paget Thomson for the discovery of electron diffraction, which helped lay the foundation for solid-state electronics.
In the early 1940s, the photovoltaic cell was developed by Russell Ohl. In 1947, the transistor, probably the most important invention developed by Bell Laboratories, was invented by John Bardeen, William Bradford Shockley, and Walter Houser Brattain (all of whom subsequently won the Nobel Prize in Physics in 1956). In 1948, "A Mathematical Theory of Communication", one of the founding works in information theory, was published by Claude Shannon in the Bell System Technical Journal; it built in part on earlier work in the field by Bell researchers Harry Nyquist and Ralph Hartley. In 1949, Bell Labs demonstrated the first remote operation of a teleprinter, which was in New Hampshire and was controlled by a computer in New York City. It also introduced a series of increasingly complex calculators through the decade.
The 1960s saw several important developments from Bell Labs, including the light-emitting diode (LED) in 1962 [verification needed], invented by Nick Holonyak. Since their invention, LEDs have been used in millions of commercial products around the world such as personal computers. In 1964, the Carbon dioxide laser was invented by Kumar Patel. In 1965, Penzias and Wilson discovered the Cosmic Microwave Background, and won the Nobel Prize in 1978. In 1966, Orthogonal frequency-division multiplexing (OFDM), a key technology in wireless services, was developed and patented by R. W. Chang. In 1968, Molecular beam epitaxy was developed by J.R. Arthur and A.Y. Cho; molecular beam epitaxy allows semiconductor chips and laser matrices to be manufactured one atomic layer at a time. In 1969, the UNIX operating system was created by Dennis Ritchie and Ken Thompson. UNIX has since been developed into more modern operating systems such as Linux and Mac OS X. The Charge-coupled device (CCD) was invented in 1969 by Willard Boyle and George E. Smith.
The 1970s and 1980s saw more and more computer-related inventions at the Bell Labs as part of the personal computing revolution. In 1970, Dennis Ritchie developed the C programming language for use in writing the UNIX operating system (also developed at Bell Labs). In 1971, a computerized switching system for telephone traffic was invented by Erna Schneider Hoover, who received one of the first software patents for it. In 1976, Fiber optics systems were first tested in Georgia and in 1980, the first single-chip 32-bit microprocessor, the BELLMAC-32A was demonstrated, it went into production in 1982. In 1980, the TDMA and CDMA digital cellular telephone technology was patented. In 1982, Fractional quantum Hall effect was discovered by Horst Störmer and former Bell Labs researchers Robert B. Laughlin and Daniel C. Tsui; they consequently won a Nobel Prize in 1998 for the discovery. In 1983, the C++ programming language was developed by Bjarne Stroustrup as an extension to the original C programming language also developed at Bell Labs.
In 1984, Karmarkar Linear Programming Algorithm was developed by mathematician Narendra Karmarkar. Also in 1984, a divestiture agreement with the American Federal government forced the break-up of AT&T: Bellcore was split off from Bell Labs to provide the same R&D functions for the newly created local exchange carriers. AT&T was also limited to using the Bell trademark only in association with Bell Labs. Bell Telephone Laboratories, Inc. was then renamed AT&T Bell Laboratories, Inc., and became a wholly owned company of the new AT&T Technologies unit, the former Western Electric. In 1985, laser cooling was used to slow and manipulate atoms by Steven Chu and team. Also in 1985, Bell Labs was awarded the National Medal of Technology for "For contribution over decades to modern communication systems". During the 1980s, the Plan 9 operating system was developed as a replacement for Unix which was also developed at Bell Labs in 1969; Development of the Radiodrum, a three dimensional electronic instrument. In 1988, TAT-8 is the first fiber optic transatlantic cable.
In 1990, WaveLAN, the first wireless local area network (LAN) was developed at Bell Labs. Wireless network technology would not become popular until the late 1990s and was first demonstrated in 1995. In 1991, the 56K modem technology was patented by Nuri Dagdeviren and his team. In 1994, the Quantum cascade laser was invented by the Federico Capasso, Alfred Cho, and their collaborators and was later greatly improved by the innovations of Claire Gmachl. In 1996, SCALPEL electron lithography, which prints features atoms wide on microchips, was invented by Lloyd Harriott and his team. The Inferno operating system, an update of Plan 9, was created by Dennis Ritchie with others, using the new concurrent Limbo programming language.
AT&T spun off Bell Labs, along with most of its equipment-manufacturing business, into a new company named Lucent Technologies. AT&T retained a smaller number of researchers, who made up the staff of the newly-created AT&T Laboratories. In 1997, 50 years after inventing the original transistor, the smallest practical transistor (60 nanometers or a mere 182 atoms wide) was built. In 1998, the first optical router was invented and the first combination of voice and data traffic on an Internet Protocol (IP) network was developed at the Labs.
2000 was a very active year for the Labs in which DNA machine prototypes were developed; progressive geometry compression algorithm made widespread 3-D communication practical; the first electrically powered organic laser invented; a large-scale map of cosmic dark matter was compiled, and F-15, an organic material that makes plastic transistors possible, was invented. In 2002, Jan Hendrik Schön, a German physicist, was fired after his work was found to contain fraudulent data -- the first case of scientific fraud in the lab's history. Over a dozen of Schön's papers were found to contain completely fictional or considerably altered data, including a paper on molecular-scale transistors that was received as a breakthrough. Also in 2002, the world's first semiconductor laser that emits light continuously and reliably over a broad spectrum of infrared wavelengths was invented. In 2003, the New Jersey Nanotechnology Laboratory was founded as the successor to Bell Laboratories at Murray Hill, New Jersey.
In 2005, Dr. Jeong Kim, former President of Lucent's Optical Network Group, returned from academia to become President of Bell Labs.
In April 2006, Bell Labs' mother company, Lucent Technologies, signed a merger agreement with Alcatel. This deal has raised concerns in the US, where Bell Labs works on highly sensitive defense contracts. It was announced that a separate company with a US board would be set up to manage Bell Labs' and Lucent's sensitive US government contracts.