Wikipedia: Bell Labs

Bell Telephone Laboratories was originally the research and development arm of the [Bell System]?, developing everything from telephone switches to specialized coverings for telephone cables, to the transistor.

In 1925 Walter Gifford (president of AT&T) established the separate entity called Bell Telephone Laboratories Inc., which took over work previously conducted by the research division of [Western Electric]?'s engineering department. Bell Labs was 50 percent owned by Western Electric, and 50 percent owned by AT&T.

The work done by Bell Labs was broadly divided into three categories: research, systems engineering and development.

Research created the theoretical underpinnings for telecommunications. It covered subjects like mathematics, physics, material sciences, behavioral sciences, computer programming theory, etc.

Systems engineering concerned itself with conceiving the highly complex systems that make up the telecommunication networks.

Development, by far the largest of Bell Labs' activities designed the specific systems -- both hardware and software -- needed to build the Bell System's telecommunications networks.

In 1933, [Karl Jansky]? in his work for Bell Labs investigating the origins of static on long distance communications, discovered that radio waves were being emitted from the centre of the Galaxy - the founding of [Radio astronomy]?, though Bell did not pursue this, being more focussed on the problems of telecommunications.
The transistor was invented by Bell Labs in 1947. The people responsible for the discovery, John Bardeen, [William Shockley]?, and [Walter Brattain]?, won the Nobel Prize in Physics in 1956.
Bell Labs developed the [photovoltaic cell]?.
Bell Labs was also the original home to the UNIX operating system and the C programming language, developed by Brian Kernighan, Dennis Ritchie, and Ken Thompson in the early 1970s, as well as the C++ programming language developed by Bjarne Stroustrup in the 1980s.