This monograph introduces readers to core theories and applications in the chatbot AI context. Although AI is attracting significant attention, there is a literature gap and lack of practical guidelines on the key drivers of chatbot efficiency and agency capacity. There is a caveat between algorithmic explanations and actionable understanding, despite the acknowledged importance of inherently human-centric properties. Addressing these gaps, this state-of-the-art book offers a distinctive combination of content, theory, practice evaluation, and a holistic framework encompassing cognitive, emotional and social aspects, focusing on how to enhance AI agency and user experience. The framework aims to drive design, encouraging development of intelligent systems, techniques to evaluate chatbot with purposes, to appropriately meet user needs and market demand for responsible and explainable AI, XAI. Avenues for transforming business and life by implementing new generation AI systems are further discussed, as well as recommendations to overcome consumer resistance and advice for policy measures to reduce risks given the AI boost. While the community is still in an exploratory mode, we hope " The Rise of AI User Applications: Chatbots Integration Foundations and Trends " provides the needed understanding and will inspire researchers across disciplines to combine their efforts and work together on this very intriguing topic.