Generators are machines that can create electricity without having to rely on any outside source. They are commonly used as a backup power supply for hospitals and other similar institutions that cannot afford to have an electrical failure. They can also be used by homeowners as a backup power supply in the event of an emergency.
Because generators have to produce usable electricity without an outside source, they are usually powered by gasoline. Depending on the size of the generator and the amount of electricity needed, fuel efficiency can vary. However, as a general rule, these machines can provide hours of electricity with only a few gallons of gas.
Choosing which generators are best for your situation might require a bit of research. The biggest determining factor is how much electricity you will require. Most of these machines are rated based on their output.