Color space
A color space defines how many colors a file can hold and show, like sRGB, Adobe RGB or ProPhoto RGB. When editing you often work internally in a wide color space, but export to a smaller one like sRGB for web and social. The right choice prevents dull or wrong colors on other people's screens.
Editing your RAW file internally in a wide color space keeps all the color information available. Always export to sRGB for the web, because that's what browsers and social media expect: skip it and your colors often look flat to others. For printing at a good print shop, Adobe RGB can be better. So match your export color space to where the photo is headed.
Read also the in-depth explanation: Color space explained.
Related terms
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The presets on this site set these adjustments up for you as a starting point, which you then fine-tune to taste.