Hybrid quantum circuits combine multiple physical systems to leverage their strengths for exploring new phenomena and developing quantum technologies. This review discusses progress in hybrid circuits involving atoms, spins, and solid-state devices like superconducting and nanomechanical systems. These circuits integrate elements from atomic physics, quantum optics, condensed matter physics, and nanoscience. Hybrid circuits can be fabricated on chips, enabling scalability crucial for quantum technologies like detectors, simulators, and computers. Atoms, spins, superconducting qubits, and resonators (optical, superconducting, nanomechanical) are key components. Cavity quantum electrodynamics (QED) explores interactions between atoms/spins and cavity photons. Theoretical principles and proposals for hybrid systems include coupling atoms/spins to superconducting resonators (without qubits) and with qubits. Direct and indirect coupling methods are discussed, along with applications in quantum circuits. Experimental realizations include direct coupling of nitrogen-vacancy centers with flux qubits and indirect coupling with transmon qubits. Hybrid circuits with nanomechanical resonators enable studies of quantum-to-classical transitions. Other hybrid systems include those with microscopic defects, topological qubits, and optical-to-microwave photon conversion. SC qubits, with strong coupling to external fields and ease of control, are central to hybrid circuits. They offer scalability and have been used in circuit QED. However, they face challenges like short coherence times due to environmental noise. Improvements in SC qubit designs, such as transmon and fluxonium qubits, have enhanced coherence times. Cavities and resonators (optical, superconducting, nanomechanical) play crucial roles in hybrid circuits. Optical cavities, superconducting resonators, and nanomechanical resonators each have unique properties and applications. Strong coupling between matter and cavity modes is essential for quantum information processing. Spin systems, including electron and nuclear spins, offer long coherence times but face challenges in quantum gate operations due to weak coupling. Spin systems can be integrated with SC circuits for hybrid quantum systems. Spin-cavity systems and spin-resonator systems have been experimentally demonstrated. SC qubits coupled to resonators enable cavity QED, where SC qubits act as artificial atoms. Strong and ultrastrong coupling regimes have been experimentally realized. Charge, flux, and phase qubits can couple to resonators via electric, magnetic, or inductive interactions. Hybrid systems combining atoms, spins, and SC circuits offer advantages in scalability, coherence times, and quantum gate operations. These systems are crucial for future quantum technologies, including quantum simulators and computers. The review highlights the progress and challenges in developing hybrid quantum circuits for quantum information processing.Hybrid quantum circuits combine multiple physical systems to leverage their strengths for exploring new phenomena and developing quantum technologies. This review discusses progress in hybrid circuits involving atoms, spins, and solid-state devices like superconducting and nanomechanical systems. These circuits integrate elements from atomic physics, quantum optics, condensed matter physics, and nanoscience. Hybrid circuits can be fabricated on chips, enabling scalability crucial for quantum technologies like detectors, simulators, and computers. Atoms, spins, superconducting qubits, and resonators (optical, superconducting, nanomechanical) are key components. Cavity quantum electrodynamics (QED) explores interactions between atoms/spins and cavity photons. Theoretical principles and proposals for hybrid systems include coupling atoms/spins to superconducting resonators (without qubits) and with qubits. Direct and indirect coupling methods are discussed, along with applications in quantum circuits. Experimental realizations include direct coupling of nitrogen-vacancy centers with flux qubits and indirect coupling with transmon qubits. Hybrid circuits with nanomechanical resonators enable studies of quantum-to-classical transitions. Other hybrid systems include those with microscopic defects, topological qubits, and optical-to-microwave photon conversion. SC qubits, with strong coupling to external fields and ease of control, are central to hybrid circuits. They offer scalability and have been used in circuit QED. However, they face challenges like short coherence times due to environmental noise. Improvements in SC qubit designs, such as transmon and fluxonium qubits, have enhanced coherence times. Cavities and resonators (optical, superconducting, nanomechanical) play crucial roles in hybrid circuits. Optical cavities, superconducting resonators, and nanomechanical resonators each have unique properties and applications. Strong coupling between matter and cavity modes is essential for quantum information processing. Spin systems, including electron and nuclear spins, offer long coherence times but face challenges in quantum gate operations due to weak coupling. Spin systems can be integrated with SC circuits for hybrid quantum systems. Spin-cavity systems and spin-resonator systems have been experimentally demonstrated. SC qubits coupled to resonators enable cavity QED, where SC qubits act as artificial atoms. Strong and ultrastrong coupling regimes have been experimentally realized. Charge, flux, and phase qubits can couple to resonators via electric, magnetic, or inductive interactions. Hybrid systems combining atoms, spins, and SC circuits offer advantages in scalability, coherence times, and quantum gate operations. These systems are crucial for future quantum technologies, including quantum simulators and computers. The review highlights the progress and challenges in developing hybrid quantum circuits for quantum information processing.