Staining is when you color something in a special way to make it easier to see. Imagine you have a white shirt with a tiny red dot on it. It is probably hard to see the dot because it blends in with the white shirt. But if you use a special marker to color the dot blue, now it stands out and is easier to see. Scientists and doctors use staining to color things like cells or tissues so they can see them better under a microscope. It helps them understand more about how our bodies work and what might be causing a problem.