A light emitting diode (LED) is a tiny, electronic semiconductor that converts electric energy into visible light. The chemical compound used within an LED determines its color, brightness and power efficiency.
Unlike incandescent lamps, LEDs have no filaments that can burn out or fail.
Manufacturers use several types of LEDs to construct digital displays. The two most common are Through-Hole LEDs and Surface Mount Device (SMD) LEDs, also known as Surface Mount Technology (SMT). Each type has its respective advantages that make them preferable for different applications.
Surface Mount LEDs
Surface Mount Devices, or SMD for short, refers to the LED lead frame mounting method. LEDs are mounted to the surface of the circuit board. The SMD contains red, green and blue die.
Through-Hole LEDs
Through-hole LEDs are mounted with leads protruding through the circuit board and appear to stand taller. Each LED is a single-color die of either red, green or blue.