Classification by PKILLERH

The term "laptop" can refer to a number of classes of small portable computers:^[15][16]

• Full-size Laptop: A laptop large enough to accommodate a "full-size" keyboard (a keyboard with the minimum QWERTY key layout, which is at least 13.5 keys across that are on ¾ (0.750) inch centers, plus some room on both ends for the case). The measurement of at least 11 inches across has been suggested as the threshold for this class^{[citation needed]}. The first laptops were the size of a standard U.S. "A size" notebook sheet of paper (8.5 × 11 inches)^{[citation needed]}, but later "A4-size" laptops were introduced, which were the width of a standard ISO 216 A4 sheet of paper (297 mm, or about 11.7 inches), and added a vertical column of keys to the right and wider screens.
• Netbook: A smaller, lighter, more portable laptop. It is also usually cheaper than a full-size laptop, but has fewer features and less computing power. Smaller keyboards can be more difficult to operate. There is no sharp line of demarcation between netbooks and inexpensive small laptops; some 11.6" models are marketed as netbooks. Since netbooks, compared to laptops, are quite small in size, CDs cannot be used in these computers.
• Tablet PC: these have touch screens. There are "convertible tablets" with a full keyboard where the screen rotates to be used atop the keyboard, and "slate" form-factor machines which are usually touch-screen only (although a few older models feature very small keyboards along the sides of the screen.)
• Rugged: Engineered to operate in tough conditions (mechanical shocks, extreme temperatures, wet and dusty environments).