During its brief existence Wikipedia has proved astonishingly successful. Its 2.8 million articles (in English alone) are available freely to all with access to the internet. The on-line encyclopaedia can be seen as the 21st century's version of earlier historical attempts to gather the world's knowledge into one place. This unique book first offers a description of some of these earlier attempts. The author discusses five historical groups or communities of practice, all of which had similar ambitions to Wikipedia to make an impact on the society of their time through the dissemination of information. The second part is an analysis of Wikipedia itself, and the third part contains suggestions about how to approach it, how to contribute to it and what one might gain from it. Writing in an accessible style the author takes a socio-historical approach and argues that by looking at communities of practice in the past we can come to understand the radical, even political, nature of Wikipedia. The book will have a broad appeal to anyone interested in the development of this unique project, including information management professionals but also historians, sociologists, educators and students.