An Inverter Generator is a closed frame generator that runs much quieter than other generators. The closed frame helps limit the noise. So if you're searching for a super quiet generator an inverter generator is what you're looking for.
They are powered by gas and more fuel efficient as the engine varies the speed it is run, depending on the power needed
Portability - Inverter generators are portable by nature (and lighter for the most part) although in some cases they will be installed, say in a camper.
They also provide more consistent power which is ideal for touchy electronic devices such as computers where power fluctuations could cause a loss of data.
The cost of an inverter generator can range from a few hundred to a few thousand dollars. Going by current top seller lists, Yamaha is rated highly by users for theirs.