Contrast
Contrast is the difference between the light and dark parts of your photo. More contrast makes the image punchier and deepens the shadows, less contrast gives a flat, soft look. The contrast slider applies this to the whole photo at once.
For finer control, reach for the tone curve instead of the global contrast slider, since it lets you choose which tones to affect. Too much contrast eats detail in the shadows and highlights, so keep an eye on your histogram. A soft, light look (like many wedding presets) actually calls for less contrast. Try pulling contrast back a touch and adding clarity or local contrast instead, for depth without harshness.
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.