To survive, humans must drink water and eat food. But that water must be clean, which means it should either be filtered or heated up to a boil. And any meat -- for example, a fish you catch the river -- must be cooked. If not, you'll get sick. That's where lifesaving technology No. 4, the camping stove, comes into play.
Sure, you can start up a roaring fire with some matches and logs, but a camping stove is much easier to ignite. And it'll get your water to boiling point and your fish cooked before you'd ever ax enough wood to make a fire.
The two main types of camping stoves are liquid fuel and canister. Canister stoves run on a mix of propane or butane gas. They're generally lightweight, but canisters can't be refilled. Once the fuel runs out, the canister is done. They also don't heat up as quickly in freezing temperatures. Liquid fuel stoves generally burn white gas. The benefit of the liquid fuel stove is that it burns hot even in very cold outdoor temperatures [source: Berger].