A thermal concentrator is a type of thermal functional device that guides and concentrates heat flux from a broad area into a specific target region by manipulating the distribution of thermal conductivity or the geometry of the structure. Its theoretical foundations primarily include coordinate transformation heat conduction theory, effective medium methods, and scattering cancellation theory, enabling precise control of both steady-state and transient heat flow. In practical applications, thermal concentrators have been widely used in fields such as microelectronics cooling, thermoelectric energy harvesting, petroleum heating, chip temperature regulation, and thermal therapy. They demonstrate unique advantages in enhancing local temperature gradients, improving thermal energy utilization, and achieving spatial thermal management. In recent years, with advances in materials science and fabrication technologies, thermal concentrators have gradually progressed from theoretical models to practical engineering applications. This paper reviews the fundamental principles, design methods, and representative applications of thermal concentrators, and further explores their future development directions in terms of novel geometric configurations, spatial dimensions, emerging energy systems, and thermal choking-related scenarios.