Gel electrophoresis
After the gel has been run by applying the electric field, you can look to see where the molecules have moved to. To do this, different stains can be applied to the gel: this allows the molecules to be seen. The stain makes the places where the molecules moved to appear as colored bands. Stains that are used to look at proteins, such as Coomassie blue, can often been seen by the human eye under normal light. Stains that are used to look at DNA, such as ethidium bromide and GelGreen, can only be seen with the help of an ultraviolet lamp.