Gel electrophoresis is a technique used to separate DNA fragments according to their size. DNA samples are loaded into wells (indentations) at one end of a gel, and an electric current is applied to pull them through the gel. When the electric field is applied to the set up the DNA being negatively charged they move towards the positive electrode. The DNA moves in the according to there size as the DNA with molecular weight move slowly while the DNA with lightweight move faster. By this movement, the bands are created which we can observe in the UV illuminator.