Three-dimensional (3D) printing, also known as additive manufacturing, has emerged as a transformative technology reshaping the landscape of dentistry and orthodontics. This book presents a comprehensive exploration of 3D printing, tracing its evolution, working principles, and modalities including stereolithography, fused deposition modeling, selective laser sintering, and digital light processing. It highlights the shift from conventional methods to digital workflows, emphasizing advantages of precision, customization, efficiency, and patient comfort. Detailed insights cover orthodontic applications ranging from diagnostic models, aligners, surgical guides, and indirect bonding trays to innovations such as directly printed clear aligners. The text also examines critical factors influencing print quality, materials science, and clinical outcomes, while addressing limitations and future research directions. Serving as both reference and guide, this book bridges technology with clinical practice, making it an essential resource for students, researchers, and orthodontists in the digital era.