Types of Computers


The desktop is a personal computer (PC) in a form intended for regular use at a single location. They come in a variety of types ranging from large vertical tower cases to small form factor models that can be tucked behind an LCD monitor. Most of these computers have separate screens and keyboards.


Mainframes are powerful computers used mainly by large organizations for critical applications, typically bulk data processing such as census, industry and consumer statistics, enterprise resource planning and financial transaction processing.


Laptops are personal computers designed for mobile use that is small and light enough for one person to rest on their lap. A laptop integrates most of the typical components of a desktop computer, including a display a keyboard, a pointing device (a touchpad) and speakers into a single unit. A laptop is powered by electricity via an AC adapter, and can be used on the go using a rechargeable battery.


Tablets are laptop PCs equipped with a stylus (a small pen-shaped instrument that is used to input commands to a computer screen, mobile device or graphics tablet) or a touchscreen. This form factor is intended to offer a more mobile PC; this PCs may be used where notebooks are impractical or unwieldy, or do not provide the needed functionality.


Netbooks (sometimes also called mini notebooks or ultraportables) are a branch of subnotebooks, a rapidly evolving category of small, lightweight and inexpensive laptop computers suited for general computing and accessing Web-based applications; they are often marketed as “companion devices”, i.e. to augment a user’s other computer access.


Handheld-PC is a term for a computer built around a form factor which is smaller than any standard laptop computer. It is sometimes referred to as a Palmtop.

Hierarchy of computer parts

  • Software: the programs and data of a computer
  • Hardware: mechanical and electronic equipment which makes up a computer
  • CPU: the brain of the computer
  • Peripherals: physical units attached to the computer
graph TD id1[Computer System] id2[Software] id3[Hardware] id4[CPU] id5[main memory] id6[RAM] id7[ROM] id8[Peripherals] id9[input/output devices] id10[Keyboard] id11[Mouse] id12[Monitor] id13[Printer] id14[storage devices] id15[Optical devices] id16[Floppy] id17[Hard drives] id18[CD] id19[DVD] id1 --> id2 id1 --> id3 id3 --> id8 id8 --> id9 id9 --> id10 id9 --> id11 id9 --> id12 id9 --> id13 id8 --> id14 id14 --> id15 id15 --> id18 id15 --> id19 id14 --> id16 id14 --> id17 id5 --> id6 id5 --> id7 id3 --> id5 id3 --> id4