Netbooks are small laptops, with screen sizes between approximately 7 and 12 inches and low power consumption. They use either an SSD (solid state disk) or a HDD (hard disk drive) for storage, have up to 2 gigabytes of RAM (but often less), lack an optical disk drive, and usually have USB, Ethernet, WiFi and often Bluetooth connectivity. The name emphasizes their use as portable Internet appliances.