This book approaches the study of patterns by emphasising the processes responsible for them; it emphasises the logical format of process-to-pattern rather than the more wasteful pattern-to-process approach. The concern is primarily with two-dimensional surfaces, which is the way most maps are used for analysis. The material is organised into sections on process models responsible for point patterns, for line patterns and then for area patterns. It represents a synthesis of the work done on patterns in a number of fields and a large literature is reviewed in the process of the synthesis. In many respects this book represents a translation of complex mathematical materials into a readable and relatively simple verbal approach to the subject and thus brings the more sophisticated aspects to a larger number of students than has been done before. The reader need only have an elementary background in statistics. The basic probability theory required by the text is given in an appendix.