Thermal paste, also known as thermal compound or thermal grease, is a thermally conductive substance applied between the CPU (Central Processing Unit) or GPU (Graphics Processing Unit) and the heatsink in a computer. Its primary function is to fill in the microscopic imperfections on the surfaces of the CPU and the heatsink, ensuring better thermal conductivity and efficient heat transfer. Without thermal paste, these tiny gaps can trap air, which is a poor conductor of heat, leading to inefficient cooling and potential overheating of the components.