A heat pipe is a highly efficient heat transfer device that uses phase change principles. It’s a sealed, vacuum tube containing a small amount of working fluid (often water). When heat is applied to one end (the evaporator), the fluid vaporizes, absorbing latent heat. The vapor rapidly travels to the cooler end (the condenser), where it condenses back to liquid, releasing the heat. The liquid then returns to the evaporator via a capillary wick structure inside the pipe. In heat sinks, heat pipes are embedded in the base to quickly “spread” heat from a small, hot source (like a CPU die) out to a large array of fins, overcoming the limited thermal conductivity of aluminum. This allows for compact, high-performance cooler designs that can handle concentrated heat loads.