This book provides the first comprehensive look at the emerging field of web document analysis. It sets the scene in this new field by combining state-of-the-art reviews of challenges and opportunities with research papers by leading researchers. Readers will find in-depth discussions on the many diverse and interdisciplinary areas within the field, including web image processing, applications of machine learning and graph theories for content extraction and web mining, adaptive web content delivery, multimedia document modeling and human interactive proofs for web security.