What's the difference between red, blue and near-infrared light?

Reviewers and brand materials describe red light (around 630-660nm) as targeting fine lines, collagen and overall rejuvenation; near-infrared (around 830-940nm) as penetrating deeper for firmness; and blue light as aimed at acne bacteria. Multi-mode or dual-spectrum masks combine these so you can switch depending on whether your goal is anti-aging or breakouts.