Blending modes
Blending modes determine how a layer mixes with the layers beneath it. Instead of just sitting on top, the layer can multiply, lighten or boost contrast, for example. It is a fast way to make light, shadow and color react to each other.
You pick the blending mode at the top of the layers panel, next to opacity. The most-used ones are Multiply (darker), Screen (lighter) and Overlay (more contrast). They are ideal for dodge & burn, texture overlays and blending in light. Tip: hold Shift and use + or - to flip through the blending modes quickly and see what fits.
Related terms
Prefer a look in one click?
The presets on this site set these adjustments up for you as a starting point, which you then fine-tune to taste.