Printers: A printer is used to print documents, photos, and anything else that appears on your screen. There are many types of printers, including inkjet, laser, and photo printers. There are even all-in-one printers, which can also scan and copy documents.


  • Scanners: A scanner allows you to copy a physical image or document and save it to your computer as a digital (computer-readable) image. Many scanners are included as part of an all-in-one printer, although you can also buy a separate flatbed or handheld scanner.
  • Speakers/headphones: Speakers and headphones are output devices, which means they send information from the computer to the user—in this case, they allow you to hear sound and music. Depending on the model, they may connect to the audio port or the USB port. Some monitors also have built-in speakers.

  • Microphones: A microphone is a type of input device, or a device that receives information from a user. You can connect a microphone to record sound or talk with someone else over the Internet. Many laptop computers come with built-in microphones.
  • Web cameras: A web camera—or webcam—is a type of input device that can record videos and take pictures. It can also transmit video over the Internet in real time, which allows for video chat or video conferencing with someone else. Many webcams also include a microphone for this reason.
  • Game controllers and joysticks: A game controller is used to control computer games. There are many other types of controllers you can use, including joysticks, although you can also use your mouse and keyboard to control most games.
  • Digital cameras: A digital camera lets you capture pictures and videos in a digital format. By connecting the camera to your computer's USB port, you can transfer the images from the camera to the computer.
  • Mobile phones, MP3 players, tablet computers, and other devices: Whenever you buy an electronic device, such as a mobile phone or MP3 player, check to see if it comes with a USB cable. If it does, this means you can most likely connect it to your computer.

Inside a computer

Have you ever looked inside a computer case, or seen pictures of the inside of one? The small parts may look complicated, but the inside of a computer case isn't really all that mysterious. This lesson will help you master some of the basic terminology and understand a bit more about what goes on inside a computer.

Motherboard

The motherboard is the computer's main circuit board. It's a thin plate that holds the CPU, memory, connectors for the hard drive and optical drives, expansion cards to control the video and audio, and connections to your computer's ports (such as USB ports). The motherboard connects directly or indirectly to every part of the computer.

CPU/processor


The central processing unit (CPU), also called a processor, is located inside the computer case on the motherboard. It is sometimes called the brain of the computer, and its job is to carry out commands. Whenever you press a key, click the mouse, or start an application, you're sending instructions to the CPU.

The CPU is usually a two-inch ceramic square with a silicon chip located inside. The chip is usually about the size of a thumbnail. The CPU fits into the motherboard's CPU socket, which is covered by the heat sink, an object that absorbs heat from the CPU.

A processor's speed is measured in megahertz (MHz), or millions of instructions per second; and gigahertz (GHz), or billions of instructions per second. A faster processor can execute instructions more quickly. However, the actual speed of the computer depends on the speed of many different components—not just the processor.


RAM (random access memory)


RAM is your system's short-term memory. Whenever your computer performs calculations, it temporarily stores the data in the RAM until it is needed.

This short-term memory disappears when the computer is turned off. If you're working on a document, spreadsheet, or other type of file, you'll need to save it to avoid losing it. When you save a file, the data is written to the hard drive, which acts as long-term storage.

RAM is measured in megabytes (MB) or gigabytes (GB). The more RAM you have, the more things your computer can do at the same time. If you don't have enough RAM, you may notice that your computer is sluggish when you have several programs open. Because of this, many people add extra RAM to their computers to improve performance.

Hard drive



The hard drive is where your software, documents, and other files are stored. The hard drive is long-term storage, which means the data is still saved even if you turn the computer off or unplug it.

When you run a program or open a file, the computer copies some of the data from the hard drive onto the RAM. When you save a file, the data is copied back to the hard drive. The faster the hard drive, the faster your computer can start up and load programs.

Power supply unit


The power supply unit in a computer converts the power from the wall outlet to the type of power needed by the computer. It sends power through cables to the motherboard and other components.

If you decide to open the computer case and take a look, make sure to unplug the computer first. Before touching the inside of the computer, you should touch a grounded metal object—or a metal part of the computer casing—to discharge any static buildup. Static electricity can be transmitted through the computer circuits, which can seriously damage your machine.