“In 1959, Ermal Fraze devised a can-opening method that would come to dominate the canned beverage market. His invention was the “pull-tab”. This eliminated the need for a separate opener tool by attaching an aluminium pull-ring lever with a rivet to a pre-scored wedge-shaped tab section of the can top. It was like having an opener tool built into every can. The ring was riveted to the center of the top, which created a wedge opening long enough so that one hole served to both let the beverage flow out while air flowed in. Into the 1970s, the pull-tab was widely popular, however its popularity came with a significant problem as people would frequently discard the pull-tabs on the ground as litter. One technique that avoided littering was to drop the pull-tab into the drink…The safety and litter problems were both eventually solved later in the 1970s with the invention of the non-removing “pop-tab”. The pull-ring was replaced with a stiff aluminium lever, and the removable tab was replaced with a pre-scored round tab that functioned similarly to the push-tab, however the raised blister was no longer needed as the riveted lever would now do the job of pushing the tab open and into the interior of the can.” Wikipedia