Tin snips are hand-operated tools and their purpose is to make the difficult task of cutting sheet metal easier for the user. The two handles, which intersect via a pivot point, have two sharp blades on either end. When the user places force upon the handles to close them together, the blades cut through the material.
The action of tin snips cutting through metal is similar to how a pair of scissors cuts through paper. Similarly to scissors, they don’t simply cut, but shear through the material.
They do this by pushing up the metal on one side of the cut line and down on the other. The two sharp blades slide against one another and through the metal, thus completing the cutting action.