Wikipedia
Íslendingabók (, Book of Icelanders; ) is a historical work dealing with early Icelandic history. The author was an Icelandic priest, Ari Þorgilsson, working in the early 12th century. The work originally existed in two different versions but only the younger one has survived. The older contained information on Norwegian kings, made use of by later writers of kings' sagas.
The priest Jón Erlendsson in Villingaholt (died 1672) in the service of bishop Brynjólfur Sveinsson made two copies of Íslendingabók (now AM 113 a fol and AM 113 b fol at the Árni Magnússon Institute for Icelandic Studies), the latter one because the bishop was unhappy with the first version. The original copied from is assumed to have dated to ca. 1200. It was lost in the course of the late 17th century, and when Árni Magnússon looked for it, it had disappeared without a trace.
Íslendingabók (, literally 'book of Icelanders') is a database created by the biotechnology company deCODE genetics, attempting to record the genealogy of all Icelanders who have ever lived, insofar as sources are available; a total of approximately 810,000 people are recorded. The database is likely to contain information on about half of all Icelanders who have lived in Iceland since its settlement. It is part of a wider scheme that has been characterised as 'one of the first, and to date most contentious' attempts to assemble a large genetic database.
Íslendingabók gets its name from the first history of Iceland, by Ari the Wise; the choice of name, and the project as a whole, has been interpreted as a public-relations excerise by deCODE, appealing to Icelandic public nationalist sentiments.