Wikipedia
Geneanet is an international genealogy database. The GeneaNet project was officially launched on December 2, 1996. Since september 2012 the GeneaNet database holds over 1 billion entries.
GeneaNet began in 1996 when several people interested in genealogy and computing, Jacques Le Marois, Jérome Abela et Julien Cassaigne, realized what a great instrument the Internet could be for their genealogical research. They then had the idea to share, in a single database, not the whole of their family trees but what French genealogists call a liste éclair. The French idiom does not translate directly into English, where such a list would be known by the more prosaic title of Surname Interests List. A liste éclair is a list of surnames which a genealogist is interested in, due to them appearing in their ancestry, associated to the locations where one's ancestors have lived. That file is often enriched with the years of the beginning and the end of which one holds information about each name.
Thus, comparing two listes éclair, it is very easy to determine if they have surnames in common and, if so, to check if these surnames are located in the same place. If, when, comparing two files, the chances of finding data in common are low, when hundreds, thousands, even hundreds of thousand files are compared, the probability of a hit are multiplied. It is with this founding idea that GeneaNet was born, since the internet is a way to exchange and compare the listes éclair of genealogists worldwide. Hence, a simple search in this "index of indices" is a way to know that a given surname, in a given location, between such and such year, is studied by a given genealogist (usually as a hobby).
One can also publish an online family tree, by sending a gedcom file to the site, or by managing the family tree directly on the Geneanet site. Geneanet is based on GeneWeb software.
The ancestor of GeneaNet was called LPF, Liste des patronymes de France, which was launched in June 1996.