Generators provide electricity by running a petrol or diesel-powered engine that turns an on-board alternator to generate electrical power. The power outlets enable the user to plug in electrical equipment, leads and appliances without needing to run off the mains power supply. Typically, the more watts equal the more items that can be powered up. Portable generators are suitable for domestic, commercial, and industrial use. Some small generators are safe to use with sensitive electrical equipment such as laptops and some are ideal for camping and caravanning.