A computer is an electronic device, operating under the control of instructions stored in its own memory. Computer is an electronic device that is designed to work with Information. The term computer is derived from the
Latin term ‘computare’, this means to calculate. Computer cannot do anything without a Program. It represents the decimal numbers through a string of binary digits.
Hardware is any part of your computer that has a physical structure, such as the computer monitor or keyboard
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Input Device - Input is the raw information entered into a computer from the input devices such as keyboard, mouse, microphone, or touchpad.
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Output Device - Hardware that shows computer data to us such as the screen, speaker, or headset.
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System Unit - The system unit, also known as a "tower" or "chassis," is the main part of a desktop computer. It includes the motherboard, CPU,
RAM, and other components.
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Storage Device - A computer storage device is any type of hardware that stores data. The most common type of storage device, which nearly all computers have, is a hard drive.
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Communications Device – Device that could make a computer send and receive data, instructions, and information to and from one or more computers.

1. Personal Computer - PCs are are what most of us use on a daily basis for work or personal use. A typical PC includes a system unit, monitor, keyboard, and mouse. Most PCs today also have a network or Internet connection, as well as ports for connecting peripheral devices, such as digital cameras, printers, scanners, speakers, external hard drives, and other components.
1.1 Desktop Computer – Is a computer that is designed to stay in a single location.
1.2 Mobile Computer - is a computer that is designed to be portable and use in any location.
2. Handle Computer - Computer small to fit on your hand
3. Game Console - Mobile computing devices designed for single or multi player video game.
4. Server - A computer that provides data to other computers. It may serve data to systems on a local area network (LAN) or a wide area network (WAN) over the Internet.
5. Client – Computer that can access the information on the server
6. Mainframes - A mainframe is an ultra high-performance computer made for high-volume, processor-intensive computing. They are typically used by large businesses and for scientific purposes.
7. Super Computer - The fastest, most powerful computer
8. Embedded Computer - A special-purpose computer that functions as a component in a largest product

Advantages
Speed,Reliability, Consistency, Storage,Communications
Disadvantages
Health Risks, Violation of Privacy, Public Safety, Impact on Labor Force, Impact on Environment
When you have two or more computers connected to each other, you have a network. The purpose of a network is to enable the sharing of files and information between multiple systems. The Internet could be described as a global network of networks. Computer networks can be connected through cables, such as Ethernet cables or phone lines, or wirelessly, using wireless networking cards that send and receive data through the air.

The system unit, also known as a "tower" or "chassis," is the main part of a desktop computer. It includes the motherboard, CPU, RAM, and other components.
A processor, or "microprocessor," is a small chip that resides in computers and other electronic devices. Its basic job is to receive input and provide the appropriate output. While this may seem like a simple task, modern processors can handle trillions of calculations per second.
Just like humans, computers rely a lot on memory. They need to process and store data, just like we do. However, computers store data in digital format, which means the information can always be called up exactly the way it was stored.

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An expansion slot is a socket on the motherboard that can hold an adapter card.
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An adapter card enhances functions of a component of the system unit and/or provides connections to peripherals.
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A port is the point at which a peripheral attaches to or communicates with a system unit.
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A connector joins a cable to a port.
Each bus inside a computer consists of set of wires that allow data to be passed back and forth. Most computers have several buses that transmit data to different parts of the machine.
A power supply is a hardware component that supplies power to an electrical device. It receives power from an electrical outlet and converts the

current from AC (alternating current) to DC (direct current), which is what the computer requires.
Input is the raw information entered into a computer from the input devices such as keyboard, mouse, microphone, or touchpad.
Keyboard- As the name implies, a keyboard is basically a board of keys.
Along with the mouse, the keyboard is one of the primary input devices used with a computer.
Mouse- As the name implies, a keyboard is basically a board of keys.
Along with the mouse, the keyboard is one of the primary input devices used with a computer
Game controller- Video games and computer games use a game
controller as the input device that directs movements and actions of onscreen objects.
Digital camera- A mobile device that allows users to take pictures and store them digitally.
Voice input- is the process of entering input by speaking into a microphone.

Video input- is the process of capturing full-motion images and storing them on a computer’s storage medium.
Data generated by a computer is referred to as output. This includes data produced at a software level, such as the result of a calculation, or at a physical level, such as a printed document.
Display Devices- A display device visually conveys text, graphics, and video information.
Printer- A printer produces text and graphics on a physical medium
Printed information is called a hard copy, or printout
Speakers, Headphones, and Ear buds- An audio output device produces music, speech, or other sounds. Most computer users attach speakers to their computers to generate higher-quality sounds for playing games, interact with multimedia presentations, listen to music, watch movies.
Data projectors- A device that takes the text and images displaying on a computer screen and projects them on a larger screen.

Interactive whiteboards- a touch-sensitive device, resembling a dryerase board, that displays the image on a connected computer screen
Force-feedback game controller- Force-feedback sends resistance to the device in response to actions of the user
Tactile output- Tactile output provides the user with a physical response from the device
The computer's primary storage stores the operating system, applications, and files and folders for users of the computer.
Capacity- Storage capacity refers to how much disk space one or more storage devices provides. It measures how much data a computer system may contain.
Storage Device- A computer storage device is any type of hardware that stores data. The most common type of storage device, which nearly all computers have, is a hard drive.
Hard Drive- The hard drive is what stores all your data. It houses the hard disk, where all your files and folders are physically located. A typical hard drive is only slightly larger than your hand, yet can hold over 100
GB of data. The data is stored on a stack of disks that are mounted inside a solid encasement.
Flash Memory Storage- Flash memory is a type of electrically erasable programmable read-only memory (EEPROM). Whew, that's a mouthful.

Cloud storage- an Internet service that provides storage to computer users to access files from any computer or Store large files instantaneously
Optical Discs- An optical disc consists of a flat, round, portable disc made of metal, plastic, and lacquer that is written and read by a laser such as
CDs and DVDs.
Other Types of Storage
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Tape is a magnetically coated ribbon of plastic capable of storing large amounts of data and information
tape drive reads and writes data and information on a tape
magnetic stripe card contains a magnetic stripe that stores information
smart card stores data on a thin microprocessor embedded in the card
Microfilm and microfiche store microscopic images of documents on a roll or sheet film.