Unlike incandescent lighting that relies on heat to cause a filament to glow and produce light as hot black body, light emitting diodes (LEDs) are semiconductors and as such must be kept cool. When LEDs produce light, heat is a by-product. Heat generated in an LED increases its temperature. As the LED’s temperature increases, the light output decreases, the light changes color, and the lifetime of the LED reduces. Temperature adversely affects both the functional performance of the LED and its longevity. As a consequence, thermal management has become the most predominant issue in solid state lighting (SSL) design.