Image Color Picker

No. It is drawn to a canvas in your browser and read back with getImageData. There is no network request at any point.

Screenshots and photographs are often in a wider colour profile than sRGB. The canvas reads sRGB values, which can differ slightly from what a design tool reports.

HSL when you are building a palette. Changing only the lightness gives you consistent tints and shades of the same hue, which is very difficult to do by hand in HEX.

Yes - take the screenshot, drop it in, and click. That is the usual way to lift a colour from a site or app you cannot inspect.

Drop the screenshot in and click the pixel. That is the reliable way to lift a brand colour from a site or app whose CSS you cannot inspect.

They describe the same colour three ways. HEX and RGB are the same numbers in different notation. HSL splits it into hue, saturation and lightness, which makes building tints and shades far easier.

Colour profile. Photos and screenshots are often in Display P3 or Adobe RGB; the canvas reads sRGB. The values are correct for the web, which is sRGB.

Zoom out and pick from a flat area. A single pixel in a gradient or a JPEG artefact is not representative of the region it sits in.