A laptop, often called a notebook or “notebook computer”, is a small, portable personal computer with a “clamshell” form factor, an alphanumeric keyboard on the lower part of the “clamshell” and a thin LCD or LED computer screen on the upper part, which is opened up to use the computer. Laptops are folded shut for transportation, and thus are suitable for mobile use. Laptops are commonly used in a variety of settings, such as at work, in education, in playing games, Internet surfing, for personal multimedia and general home computer use.

A standard laptop combines the components, inputs, outputs, and capabilities of a desktop computer, including the display screen, small speakers, a keyboard, hard disk drive, optical disc drive pointing devices (such as a touchpad or trackpad), a processor, 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, makes, models and price points.

Design elements, form factor and construction can also vary significantly between models depending on 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 for traveling sales representatives. As portable computers evolved into the modern laptop, they became widely used for a variety of purposes.