Guides for connecting RGB led strips like WS2812B, which can be addressed individually, often suggest to add a capacitor in front. For example, the NeoPixel Guide states that
Before connecting NeoPixels to any large power source (DC “wall wart” or even a large battery), add a capacitor (1000 µF, 6.3V or higher) across the + and – terminals […] The capacitor buffers sudden changes in the current drawn by the strip.
But why would I want to buffer that? What happens if I don’t add a capacitor?
fyi – I do not have a background in electronics, and I probably lack fundamentas here.