Needless to say, we cant live without computer anymore, we use them everyday, we use them to deal with nearly everything. Computer becomes a part of our live. With the development of computer technology, we can deal with our daily task using computer, so we can stay at home to work. I often say that internet is the most famous creation of our society till now. With computer and internet, the all world is in our hands. We cant imagine how powerful they are. Some people predict robots will work for us, so we neednt work anymore, this is quite possible.

Computers have been around for about fifty years or so. ENIAC, the first great electronic computer, was built in the 1940th; it was the size of a large house, was limited in power and was unreliable. But computers developed quickly. Today computers sit comfortably on our desks and have much more power than those original machines. In the last ten years or so, most large businesses have become completely dependent on computers for storing and looking at information, for writing and for calculating financial and mathematical information. Computers within a single office or building may be connected, and they therefore form a network. Users of computers on a network can send messages to each other, utilizing the same collections of data or information. In many offices and organizations computer messages have replaced messages written on paper, and they are now called or electronic mail. is not only fast and easy (if you understand how to use the computer), but it also saves paper and the work of moving paper from one place to another. Workers can send and receive without leaving their desks and their desktop computers

A laptop computer or simply laptop, also called a notebook computer or sometimes a notebook, is a small personal computer designed for portability. Usually all of the interface hardware needed to operate the laptop, such as USB ports (previously parallel and serial ports), graphics card, sound channel, etc., are built in to a single unit. Laptops contain high capacity batteries that can power the device for extensive periods of time, enhancing portability. Once the battery charge is depleted, it will have to be recharged through a power outlet. In the interest of saving power, weight and space, they usually share RAM with the video channel, slowing their performance compared to an equivalent desktop machinelaptopUSB ports parallelserial portsbatteries

Netbooks (also called mini notebooks or subnotebooks) are a rapidly evolving category of small, light and inexpensive laptop computers suited for general computing and accessing web-based applications; they are often marketed as "companion devices," that is, to augment a user's other computer access. Walt Mossberg called them a "relatively new category of small, light, minimalist and cheap laptops." By August 2009, CNET called netbooks "nothing more than smaller, cheaper notebooks." Netbooks subnotebookslaptop computersweb-based applicationsWalt MossbergCNET

A tablet PC is a notebook or slate-shaped mobile computer. Its touchscreen or graphics tablet/screen hybrid technology allows the user to operate the computer with a stylus or digital pen, or a fingertip, instead of a keyboard or mouse. The form factor offers a more mobile way to interact with a computer. Tablet PCs are often used where normal notebooks are impractical or unwieldy, or do not provide the needed functionality.notebook mobile computertouchscreengraphics tablet/screen hybridstylus

The ultra-mobile PC (UMPC) is a specification for a small form factor of tablet PCs. It was developed as a joint development exercise by Microsoft, Intel, and Samsung, among others. Current UMPCs typically feature the Windows XP, Windows Vista, Windows 7, or Linux operating system and low-voltage Intel Atom or VIA C7-M processors.small form factortablet PCsMicrosoftIntelSamsungoperating system AtomVIA C7-M

An ultra-low-cost personal computer (ULCPC) is an inexpensive personal computer such as a netbook or a nettop. It is most often used by Microsoft to define a class of computers which are eligible for special licensing and discounts. For example, the availability of Windows XP has been extended and discounts are offered for ULCPCs. Microsoft have recently been relaxing the definition to include larger displays (up to 14.1") and touchscreens.netbooknettopMicrosoft

A pocket PC is a hardware specification for a handheld-sized computer (personal digital assistant) that runs the Microsoft Windows Mobile operating system. It may have the capability to run an alternative operating system like NetBSD or Linux. It has many of the capabilities of modern desktop PCs.personal digital assistantMicrosoftWindows Mobileoperating systemoperating systemNetBSDLinuxPCs