the typical components of a desktop computer, including a display, a keyboard, a pointing device (a touchpad, also known as a trackpad, and/or a pointing stick), speakers, as well as a battery, into a single small and light unit. The rechargeable battery required is charged from an AC/DC adapter and typically stores enough energy to run the laptop for two to three ours in its initial state, depending on the configuration and power management of the omputer.Laptops are usually shaped like a large notebook with thicknesses between 0.7–1.5 inches (18–38 mm) and ensions ranging from 10x8 inches (27x22cm, 13" display) to 15x11 inches (39x28cm, 17" display) and up. Modern laptops weigh 3 to 12 pounds (1.4 to 5.4 kg); older laptops were usually heavier. Most laptops are designed in the flip form factor to protect the screen and the keyboard when closed. Modern 'tablet' laptops have a complex joint between the keyboard housing and the display, permitting the display panel to twist and then lay flat on the keyboard housing. They usually have a touchscreen display and some include handwriting recognition or graphics drawing capability.Laptops were originally considered to be "a small niche market" and were thought suitable mostly for "specialized field applications" such as "the military, the Internal Revenue Service, accountants and sales representatives". Battery-powered portable computers had just 2% worldwide market share in 1986. But today, there are already more laptops than desktops in businesses, and laptops are becoming obligatory for student use and more popular for general use. In 2008 more laptops than desktops were sold in the US and according to a forecast by the research firm IDC and Intel, the same milestone will be achieved in the worldwide PC market as soon as 2009.Contents[hide] * 1 History * 2 Classification o 2.1 As replacement o 2.2 Notebook o 2.3 Subnotebook o 2.4 Netbook o 2.5 Rugged Laptop * 3 Components o 3.1 Docking stations o 3.2 Standards * 4 Advantages * 5 Disadvantages o 5.1 Performance o 5.2 Upgradeability o 5.3 Ergonomics and health o 5.4 Durability o 5.5 Security * 6 Major brands and manufacturers * 7 Sales * 8 See also * 9 References Historyain article: History of laptopshe Epson HX-20As the personal computer became feasible in the early 1970s, the idea of a portable personal computer followed. In particular, a "personal, portable information manipulator" was imagined by Alan Kay at Xerox PARC in 1968 and described in his 1972 paper as the "Dynabook".The I.B.M. SCAMP project (Special Computer APL Machine Portable), was demonstrated in 1973. This prototype was based on the PALM processor (Put All Logic In Microcode).The I.B.M. 5100, the first commercially available portable computer, appeared in September 1975, and was based on the SCAMP prototype.As 8-bit CPU machines became widely accepted, the number of portables increased rapidly. The Osborne 1 used the Zilog Z80, weighed 23.5 pounds (10.7 kg). It had no battery, only a tiny 5" CRT screen and dual 5¼" single-density floppy drives. In the same year the first laptop-sized portable computer, the Epson HX-20, was announced. The Epson had a LCD screen, a rechargeable battery and a calculator-size printer in a 1.6 kg (4 pounds) chassis. Both Tandy/Radio Shack and HP also produced portable computers of varying designs during this period.The first laptop using the clamshell design, used today by almost all laptops, appeared in 1982. The $8150 GRiD Compass 1100 was used at NASA and by the military among others. The Gavilan SC, released in 1983, was the first notebook marketed using the term "laptop".From 1983 onwards: * Several new input techniques were developed and included in laptops: the touchpad (Gavilan SC, 1983), the pointing stick (IBM ThinkPad 700, 1992) and handwriting recognition (Linus Write-Top, 1987). * Some CPUs were designed specifically for low power use (including laptops (Intel i386SL, 1990), and were supported by dynamic power management features (Intel SpeedStep and AMD PowerNow!) in some designs. * Displays reached VGA resolution by 1988 (Compaq SLT 286) and 256-color screens by 1993 (PowerBook 165c), progressing quickly to millions of colors and high resolutions. * High-capacity hard drives and optical storage (CD-ROM followed CD-R and CD-RW and eventually by DVD-ROM and the writable varieties) became available in laptops soon after their introduction to the desktops.Early laptops often had proprietary and incompatible system architectures, operating systems, and bundled applications, making third party hardware and software difficult and sometimes impossible to develop.