Can opener and its uses

A can opener opens "tin cans" (though they do not contain much tin now in the manufacturing process).

A metal can opener first punctures the lid of the can, then is manually clamped down onto the lip of the can. The lip is the raised edge around the lid. The manual opener then works from a human turning a wheel on the opener. This action begins to "cut" the metal on the inside of the lip / outsider edge of the lid. The opener contains a magnet that attaches to the lid, so when it is completely cut, the lid can be lifted off. The edges of the lid may be ragged; it can cut skin. The lid is thrown away; the food is removed and the can is thrown away.

An electric can opener operates on the same principles: using a lever, clamp, magnet, wheel, and a turning action. The main difference is less work for a human.

Some men or military personnel use a knife with a second edge on it. This uses manual force to puncture the lid and to go around the lid. The edge is very jagged. A knife carries more risks.