The WS2812B (or "NeoPixel") may look like a common 5050-sized (5x5mm) SMD LED, but there’s actually an integrated control circuit embedded inside there too. If you look really hard, you can see the tiny black chip hidden in there, along with minuscule gold wires connecting the chip to the LED. This LED is certainly more than meets the eye! The 'B' at the end of the WS2812 name denotes that these specific LEDs are equipped with and only require FOUR pins instead of SIX!
The LED itself is unlike most RGB (Red/Green/Blue) LEDs. The brightness of each color can be adjusted using a serial string to one of 256 different levels. That means there are 16,777,216 (2563) possible combinations of colors. You can produce any color from white to black (off), or salmon to sienna.