A color picker is a control for choosing a color. It may show a palette, a wheel, or a small preview that opens more choices. It is like selecting a paint color before decorating a room: the person can see the choice before using it.
For example, a design tool might let someone choose the background color of a button. Some pickers also accept a code that identifies an exact color, while others are meant for quick visual choices.
Show the selected color clearly and provide another way to recognize it, such as a name or value. Color alone should not be the only clue that tells someone which choice is active.