A laptop, laptop computer, or notebook computer is a small, portable personal computer (PC) with a screen and alphanumeric keyboard. Laptops typically have a clam shell form factor with the screen mounted on the inside of the upper lid and the keyboard on the inside of the lower lid, although 2-in-1 PCs with a detachable keyboard are often marketed as laptops or as having a laptop mode. Laptops are folded shut for transportation, and thus are suitable for mobile use.[1] They are so named because they can be practically placed on a person's lap when being used. Today, laptops are used in a variety of settings, such as at work, in education, for playing games, web browsing, for personal multimedia, and for general home computer use.

As of 2021, in American English, the terms laptop computer and notebook computer are used interchangeably;[2] in other dialects of English, one or the other may be preferred. Although the terms notebook computers or notebooks originally referred to a specific size of laptop (originally smaller and lighter than mainstream laptops of the time),[3] the terms have come to mean the same thing and notebook no longer refers to any specific size.

Laptops combine all the input/output components and capabilities of a desktop computer, including the display screen, small speakers, a keyboard, data storage device, sometimes an optical disc drive, pointing devices (such as a touch pad or pointing stick), with an operating system, a processor (Central processing unit (CPU)) and memory into a single unit. Most modern laptops feature integrated webcams and built-in microphones, while many also have touchscreens. Laptops can be powered either from an internal battery or by an external power supply from an AC adapter. Hardware specifications, such as the processor speed and memory capacity, significantly vary between different types, models and price points.

Design elements, form factor and construction can also vary significantly between models depending on the intended use. Examples of specialized models of laptops include rugged notebooks for use in construction or military applications, as well as low production cost laptops such as those from the One Laptop per Child (OLPC) organization, which incorporate features like solar charging and semi-flexible components not found on most laptop computers. Portable computers, which later developed into modern laptops, were originally considered to be a small niche market, mostly for specialized field applications, such as in the military, for accountants, or traveling sales representatives. As portable computers evolved into modern laptops, they became widely used for a variety of purposes.[4]