The aim of this book is to provide an up-to-date review of different approaches to clas-sification, compare their performance on a wide range of challenging data-sets, and drawconclusions on their applicability to realistic industrial problems.Before describing the contents, we first need to define what we mean by classification,give some background to the different perspectives on the task, and introduce the EuropeanCommunity StatLog project whose results form the basis for this book.