This book serves both as a textbook for forensic linguistics and as a practical guide for identifying anonymous authors through their language patterns. It illustrates, through numerous examples, the multifaceted information that texts and sentences reveal about their authors. The focus is on qualitative methods, which include a meaningful coding system that has proven effective in the long-standing practice of the author as a publicly appointed and sworn expert. This accessible and essential guide contains a comprehensive glossary of technical terms, addresses the current issue of AI-generated texts, and is aimed not only at linguists but also at readers from the fields of law (particularly judges), computer science, psychology, criminology, and criminalistics.