This chapter explores the fundamentals of quantum technology, explaining key principles such as superposition, entanglement, and quantum tunneling that differentiate quantum computing from classical computing. It introduces Quantum System-on-Chip (SOC) designs, detailing their components, including quantum processing units (QPUs), control electronics, cryogenic compatibility, and quantum communication interfaces, which enable scalable and efficient quantum computing. The chapter discusses application domains like cryptography, optimization, AI, and materials science while addressing security risks posed by quantum threats, such as breaking modern encryption methods. Finally, it examines the challenges and approaches to designing Quantum SOCs, emphasizing advancements in quantum logic design, error correction, and emerging electronic design automation (EDA) tools for quantum circuits.