The Art of Chunking in AI Systems: Foundation and Core Techniques is a comprehensive guide to one of the most fundamental components of modern Retrieval-Augmented Generation (RAG) systems. While significant attention has been devoted to large language models, embeddings, and vector databases, the process of chunking remains comparatively underexplored despite its critical influence on retrieval quality and AI performance. This book provides a structured introduction to the principles, techniques, and practical considerations of chunking in AI systems. It begins by establishing the foundations of Retrieval-Augmented Generation, explaining why retrieval continues to play a vital role in enhancing the accuracy, reliability, and contextual understanding of language models. Readers are then introduced to the complete taxonomy of chunking methods, ranging from traditional fixed-length approaches to advanced dynamic strategies. Topics include character-based chunking, token-based chunking, slidingwindow techniques, semantic chunking, document-specific chunking, code-aware chunking, hierarchical chunking, and the emerging concept of agentic chunking. Each technique is presented with its underlying principles, advantages, limitations, suitable applications, and practical recommendations. Rather than advocating a single "best" method, the book emphasises that effective chunking depends on the characteristics of the data, retrieval objectives, embedding models, and downstream AI applications. It provides readers with a practical framework for selecting, comparing, and evaluating chunking strategies based on real-world requirements. Designed for students, researchers, educators, AI practitioners, and software developers, this book combines theoretical concepts with practical insights to build a strong foundation in chunking methodologies. Whether you are developing knowledge assistants, enterprise search systems, document question-answering applications, or other RAG-based solutions, this book offers the essential concepts needed to design more accurate, efficient, and scalable retrieval systems. As the first volume in the The Art of Chunking in AI Systems series, this book lays the conceptual groundwork for advanced topics that will be explored in subsequent volumes, including chunk evaluation, optimisation techniques, adaptive retrieval, multimodal chunking, and next-generation intelligent retrieval architectures.