In 1960, zip tops made opening aluminum cans more convenient – and dangerous. Those razor-sharp metal tags you ripped off and threw away were a hazard for the thirsty.
That all changed in 1972, when a young engineer named Daniel Cudzik was hired by the Reynolds Metals Company to help them enter the fledgling aluminum can business. Since its invention, Cudzik's pop-tab has by one estimate conserved half a billion pounds of aluminum, and quite a few thumbs.
See the design: Daniel Cudzik's original patent application, with drawings, for an aluminum can with an "easy open wall."