Standard analog RGB leds require 4 wires per LED and PWM signals to modulate their intensity, so applications with many of those leds are complicated to implement and require a lot of pins on your MCU, or an additionnal IC.
WS2812B leds are RGB leds that integrate a logic circuit with a serial port/bridge. Their connection is very simple since only 3 wires are needed to drive a group of several dozens of leds connected to each other, each led being independently controllable in color and intensity !
