The global brain is a conceptualization of the worldwide network formed by all the people on this planet together with the information and communication technologies that connect them into an intelligent, Self Organizing system. As the Internet becomes faster, more intelligent, and more encompassing, it increasingly ties us together into a single information processing system, which functions like a Nervous System for the planet Earth. The intelligence of this network is collective or distributed: it is not centralized or localized in any particular individual, organization or computer system. It rather emerges from the dynamic networks of interactions between its components, a property typical of Complex Adaptive Systems.
Although the underlying ideas are much older, the term "global brain" was apparently coined in 1982 by Peter Russell in his book The Global Brain. How the Internet might be developed to achieve this was set out in 1986 . The first peer-refereed article on the subject was published by Mayer-Kress and Barczys in 1995, while the first algorithms that could turn the world-wide web into a collectively intelligent network were proposed by Francis Heylighen and Johan Bollen in 1996.
The mental aspects of such an organic system at the planetary level were perhaps first broadly elaborated by paleontologist and Jesuit priest Pierre Teilhard De Chardin. In 1945, he described a coming "planetisation" of humanity, which he saw as the next phase of accelerating human "socialisation" (British spellings). Teilhard described both socialization and planetization as irreversible, irresistible processes of macrobiological development culminating in the emergence of a NooSphere, or global mind (see Emergentism below). http://en.wikipedia.org/wiki/Global_brain