HEX, RGB and HSL
HEX codes such as #0071E3 are used in web design, Canva, Figma and most design apps. RGB gives the red, green and blue values from 0 to 255, which some apps and code ask for. HSL describes hue, saturation and lightness, which makes it easy to create lighter or darker versions of a colour.
The picker averages a tiny 3 × 3 pixel area, so a single stray pixel in a photo doesn't throw the result off.
Building a palette from a photo
The main colours are found by grouping similar pixels together and are listed from most to least common, with roughly how much of the image each one covers. It's a quick way to match a brand, decorate a room from a favourite picture or pick colours for a slide deck that suit your photos.