Quantum computing is a new field that uses the rules of quantum mechanics to solve problems that classical computers cannot handle. This chapter introduces the foundational concepts that make quantum computers fundamentally distinct, including superposition, entanglement, and quantum bits (qubits). It traces the evolution of the field from theoretical foundations to present-day experimental implementations, highlighting significant milestones in hardware and algorithmic development. The discussion covers essential quantum theory concepts, including quantum states, measurement, and the operation of quantum gates, as well as a comparison between classical bits and qubits. Key quantum algorithms, including Shor’s and Grover’s, are explained in the context of their computational advantages. The chapter also examines different types of quantum computers, current technological platforms, and the engineering challenges in scaling them. Applications across domains such as cryptography, drug discovery, materials science, logistics optimization, and Machine Learning (ML) are explored, with a focus on the transformative potential of quantum computing. The chapter concludes by discussing current limitations, like error correction and decoherence, and highlights promising avenues for future research. This thorough overview provides readers with a clear grasp of what quantum computing entails, its mechanisms, and future directions.