A laptop combines the components and inputs as a desktop computer; including display,speakers keyboard, and pointing device (such as a touchpad), into a single device. Most modern-day laptop computers also have a webcam and a mic (microphone) pre-installed] A laptop can be powered either from arechargeable battery, or by mains electricity via an AC adapter. Laptops are a diverse category of devices, and other more specific terms, such asultrabooks or netbooks, refer to specialist typesof laptop which have been optimised for certain uses. Hardware specifications change vastly between these classifications, forgoing greater and greater degrees of processing power to reduce heat emissions.