Introduction Science has produced many new discoveries since the rst edition of this book appeared in 1995. Apart from its general structure, nothing remains from that rst edition and very little from the second edition. Nearly all the material used for the rst edition was only available in printed form, while references had to be individually and laboriously word processed. Nowadays the database “cite” function makes compiling reference lists much less onerous. Powerful search engines have made nding relevant information much easier. Vastly enhanced access to information and the speed with which it can now be located make it imperative to adequately represent the ndings from this feature of contemporary communication. Enhanced availability of knowledge has correspondingly increased authors’ responsibility to ensure that their material is up-to-date and highly germane to their specialist topic. The rate at which knowledge advances in many areas of science means that this is an increasing challenge, particularly in cases, as in ours, where we seek to represent relevant new knowledge across a range of disciplinary areas. These features have also shortened the lead time between laying the foundations for a new edition and its publication.