There are several ways to open a canned food. Ways may vary depending on situation and on how the package was built.
1) The modern can opener. The device consist of two levers, two sharp rollers and a screw. It works by clipping the rollers on can seam. The rollers will run around by turning the butterfly screw / lever continuously.
It is perfect for opening a canned meat loaf. Open both ends. Then the contents can be pushed out with less scratches.
2) The simple can opener, lever type. It consist of a lever and a hook wedge. It works by clipping on side of can seam. Then the cut is made by up and down motion of the lever. It creates a numerous protruding sharp edges on tin cover and can lining. Getting out the food with bare hand is not recommended.
3) Knife. Whenever a can opener is not available, the versatile kitchen knife is to the rescue. The downside, it can create a wound on hand of the doer. Extreme care should be observed.
4) Spoon. Hold the spoon firmly with right hand. Hold the can firmly with the left hand. Then rub the spoon tip on can until the opening is made. Repeat until the whole top cover is remove.
This made my hand achy the whole day. The worst, the can was only half opened. Strong men can do it with ease. I am not as strong as them, obviously.
5) Key opener. A key comes with the can. The key is inserted to provided hole. Then turned around until opened. Common in corned beef products.
6) The easy open can. Can opener of any kind is not needed. The can has a built in lever. Opening is as easy as pulling it. How convenient and lazy!