Despite their increasing popularity for natural resource applications, nearest neighbor techniques remain an ad hoc collection that has yet to be systemized into a coherent, consistent body of methods. Important criticisms of the literature include lack of common vocabulary and notation, lack of diagnostic tools, and lack of documented techniques. This book aims to reverse this trend and be an introductory, readily accessible work to everyone from undergraduates and researchers with minimal statistical background, right up to scientific researchers in various fields.