A blend mode is the formula applied where two layers meet. Additive blending sums light, pushing toward white, the native mode of glows and stage-friendly brightness. Multiply darkens, screen lightens gently, difference produces electric inversions.
VJ mixing is largely blend-mode fluency: additive layers over black compose like light itself, which is why performance content ships on black backgrounds and why LED walls love additive stacks.
In render pipelines the same arithmetic runs inside effects: feedback accumulations, particle glow, and bloom composites are blend modes applied per frame. The handful of formulas is small; the craft is knowing which one a moment needs.