A scoreline is the fine embossed line on a can along which the metal is designed to tear when the can is opened with a ring-pull or a key. The line is scored, partially cut, into the lid during manufacture to a precise depth: deep enough to break cleanly under the leverage of the tab, shallow enough to maintain the hermetic seal through processing, transport, and storage. Getting that depth right is exacting engineering, since a fraction of a millimetre decides between easy opening and failure. Scored ends appear on drinks cans, sardine tins opened with keys, and easy-open food cans. The scoreline is the can’s planned weakness, put there deliberately so the consumer’s strength is applied exactly where it opens the pack.