Many people own electric can openers. When the power goes out they do not work. You will need a manual can opener. Many cans now days have pull tops on top of the cans. There are still many cans that do not have that and you will need a can opener to open them up. There are many types and kinds of can openers and brands to buy.
Get one for your kitchen, one for your 72 hour kit, and one as a back up and put in your food storage area.