The importance of `wide-field imaging' in astronomy has never been so evident. The major new deep photographic surveys of the sky are nearing completion. The advent of large-format solid state detectors will provide further deep digital sky survey data. Optical surveys of the sky are being complemented by surveys in other wavebands of the electromagnetic spectrum, principally in the X-ray and near-infrared. The mass of digital data being gathered is driving the need for mass-storage archival capability, and for rapid capabilities in data acquisitioning and processing. New techniques are being developed to optimise the extraction of the information content. The quality and quantity of data now available to astronomers are enabling major new breakthroughs in many fields, e.g. studies of the structure of our own galaxy and properties of nearby galaxies, the large-scale distribution of galaxies and the nature of the mass-content of the Universe. All these facets of wide-field astronomy are brought together (for the very first time) in this book.