Recent advances in drug delivery systems have shifted therapeutic strategies toward minimally invasive, patient-centered, and precision-based approaches. This chapter introduces the evolving landscape of modern drug delivery, highlighting the limitations of conventional administration routes and the growing demand for safer, more efficient, and self-administered therapies. Particular emphasis is placed on microneedle technologies as a transformative platform capable of improving patient compliance, enabling controlled and responsive drug release, and supporting personalized treatment strategies. Key breakthroughs in microneedle materials, including biodegradable polymers, composite structures, and stimuli-responsive systems, are discussed alongside advances in fabrication techniques and clinical translation. The chapter further examines the critical role of three-dimensional (3D) printing in medical device innovation, enabling enhanced design precision, rapid prototyping, and customizable microneedle architectures. By integrating developments in materials science, additive manufacturing, and personalized medicine, this chapter outlines the objectives and scope of the book and establishes the foundation for understanding the technological, clinical, and translational advancements shaping next-generation 3D-printed microneedle systems.