Put simply, value is the lightness or darkness of a color. It’s not about the color itself (like red or blue), but how much light that color reflects. Think of it as your whole image’s volume knob—turn it up, you get bright highlights; turn it down, you get deep shadows.
If you squint your eyes right now at any scene—say, your laptop screen and the wall behind it—you’ll see the values separate into blobs of dark and light. That’s your brain doing the work, even if you didn’t know it was looking for it.
