One of my favourite elements are LEDs. (light emitting diodes)
The greatest advantage of them: You can see if your project works immediately. But the old fashioned singe-color LEDs are boring and the RGB-LEDs need three different channels (per LED!) of your microcontroller. Another disadvantage of this standard-LEDs is that you need to use PWM to dim them.
The WS2812B solves this issues. They have also four pins but with a different purpose: VCC, GND, data-in and data-out. So you might assume that we can chain them ==> Yes you are right! But it comes even better: You can address every single LED.
So if we assume that we have 8 LEDs you would need 24 channels when you use a standard-LED but still only one channel if you use the WS2812B.