Concerted research effort since the nineteen fifties has lead to effective methods for retrieval of relevant documents from homogeneous collections of text, such as r archives, scientific abstracts and CD-ROM encyclopaedias. However, the triumph of the Web in the nineteen nineties forced a significant paradigm shift in the Information Retrieval field because of the need to address the issues of enormous scale, fluid collection definition, great heterogeneity, unfettered interlinking, democratic publishing, the presence of adversaries and most of all the diversity of purposes for which Web search may be used. Now, the IR field is confronted with a challenge of similarly daunting dimensions – how to bring highly effective search to the complex information spaces within enterprises. Overcoming the challenge would bring massive economic benefit, but victory is far from assured. The present work characterises enterprise search, hints at its economic magnitude, states some of t...