Anything outside the case that connects to your computer is considered a peripheral. The keyboard, mouse and monitor are pretty much the bare minimum you can go with and still be able to interact with your computer. Your choice in peripherals depends on personal preference and what you intend to do with your computer.

Mouse and Keyboard
There are, broadly, two types of mouse: optical and mechanical. Mechanical mice use a rubber coated ball bearing that contacts the mousepad or other surface and actually rolls around. Optical mice use a bright light and a sensor to track the movement of the mouse.

When choosing a mouse, there is generally no reason not to choose an optical mouse. They are considerably lighter (and as such, reduce RSI) as they have no moving parts, they are much better at smoothly tracking movement, and they don’t require constant cleaning like ball mice (though it may be wise to brush off the lens with a q-tip or other soft tool on occasion). Make sure that you spend money on a decent-quality mouse made by companies such as Microsoft or Logitech, as lower-end optical mice will skip if moved too fast. Mice of medium-to-high quality will track your movement almost flawlessly.

Although three buttons are generally enough for operating a computer in normal circumstances, extra buttons can come in handy, as you can add set actions to each button, and they can come in handy for playing various video games. One thing to note is that with some mice those extra buttons are not actually seen by the computer itself as extra buttons and will not work properly in games. These buttons use software provided by the manufacturer to function. However, it is sometimes possible to configure the software to map the button to act like a certain keyboard key so that it will be possible to use it in games in this manner.

Wireless keyboards and mice do not now display the sort of noticeable delay that they once did, and now also have considerably improved battery life. However, gamers may still want to avoid wireless input devices because the very slight delay may impact gaming activities, though some of the higher end models have less trouble with this. The extra weight of the batteries can also be an inconvenience.

Printer and Scanner
For most purposes, a mid-range inkjet printer will work well for most people. If you plan on printing photos, you will want one that is capable of printing at around 4800dpi. Also, you will want to compare the speed of various printers, which is usually listed in ppm (pages per minute). When choosing a printer, always check how much new cartridges cost, as replacement cartridges can quickly outweigh the actual printer’s cost. Be aware of other possible quirks as well. For example, Epson has protection measures that make refilling your own ink cartridges more difficult because an embedded microchip that keeps track of how much ink has been used keeps the printer from seeing the cartridge as full once it has been emptied.

For office users that plan to do quite a bit of black and white printing buying a black and white laser printer is now an affordable option, and the savings and speed can quickly add up for home office users printing more than 500 pages a month.

Scanners are useful, especially in office settings, they can function with your printer as a photocopier, and with software can also interact with your modem to send Faxes. When purchasing a Scanner, check to see how “accessible” it is (does it have one-touch buttons), and check how good the scanning quality is, before you leave the store if possible.

Finally, “Multi-Function Centres” (also called “Printer-Scanner-Copiers”) are often a cost-effective solution to purchasing both, as they take up only one port on your computer, and one power point, but remember that they can be a liability, since if one component breaks down, both may need to be replaced.

Display
When choosing a display for your computer, you have two choices: a Cathode Ray Tube (CRT) screen, or a Liquid Crystal Display (LCD) screen. Both technologies have their advantages and disadvantages but CRT’s, now nearly obsolete, are almost unavailable new – making the argument moot. Used CRT’s on the other hand, can be had nearly for free and still work if you have the room for them.

LCD Panels
Liquid Crystal Displays (LCDs) have the advantage of being a completely digital setup, when used with the DVI-D or HDMI digital connectors. When running at the screen’s native resolution, this can result in the most stable and sharp image available on current monitors. Many LCD panel displays are sold with an analog 15-pin VGA connector or, rarely, with an analog DVI-I connector. Such displays will be a bit fuzzier than their digital counterparts, and are generally not preferred over a similarly-sized CRT. If you want an LCD display, be sure to choose a digital setup if you can; however, manufacturers have chosen to use this feature for price differentiation.

The prime disadvantage of LCDs is “dead pixels”, small, failed areas on your monitor, which can be very annoying, but generally aren’t covered under warranty; this can make purchasing LCD displays a financial risk. In fact, most LCD panel manufacturers allow for a certain number of dead pixels in their product specification.

LCDs are acceptable for fast-paced gaming, but you should be sure that your screen has a fairly fast response time (of 12 ms or lower) if you want to play fast games. Nearly all flat panels sold today meet this requirement, some by a factor of 3.

When picking an LCD, keep in mind that they are designed to display at one resolution only, so, to reap the benefits of your screen, your graphics card must be capable of displaying at that resolution. That in mind, they can display lower resolutions with a black frame around the outside (which means your entire screen isn’t filled), or by stretching the image (which leads to much lower quality). Running at a higher resolution than your monitor can handle will either make everything on the screen smaller, at a significant quality drop, or will display only a part of the screen at a time.

CRT Displays
The other key type of display is the Cathode Ray Tube (CRT) display. While CRT technology is older, it often outperforms LCD technology in terms of color reproduction (color gamut), although LCD displays are quickly catching up. CRTs are becoming increasingly difficult to find and have almost vanished from mass-market retail. High end CRT’s are still available, though they are rapidly being discontinued, and now cost a considerable amount.

There are two types of CRT displays, shadow mask and aperture grill. An aperture grill display is brighter and perfectly flat in the vertical direction, but is more fragile and has one or two mostly-unnoticeable thin black lines (support wires) running across the screen. CRTs are generally two to four times as deep as similarly-sized LCDs, and can weigh around 10 times as much. If you purchase a CRT display over the Internet, shipping is much more expensive than an LCD, due to the significantly greater weight.

Sometimes CRTs with a flat screen instead of a curved one are called “flat screens”. This is not to be confused with the term “flat panel”, used to refer to LCDs. In order to withstand atmospheric pressure, the glass at the front of a flat screen CRT needs to be very thick, and thus they are limited to diagonal sizes of 20 inches, or so. A flat screen CRT will be noticeably heavier than its curved screen counterpart.

For improved contrast and readability, some CRTs were manufactured with an anti-reflection coating. Such tubes make colors appear more vibrant and blacks appear jet black. Also, if the user has a light from behind, such as from a lighting fixture or windows, annoying reflections on the screen will be much less noticeable. The coating typically consists of magnesium fluoride, the same material used to coat binocular optics and some corrective eyeglass lenses. It is relatively soft, and must be cleaned with care, using special lens cleaning cloths or papers to prevent scratching of the coating. Another way to clean them is with a boiled 100% cotton flannel cloth and commercial glass cleaning solution, such as Windex. Oily fingerprints show up very clearly on coated screens, so one should avoid touching them. With reasonable care, however, the screen may only need to be wet-cleaned once a year and in the meantime can be wiped with a soft dust cloth or brushed with a soft, natural-bristle paint brush to remove any dust that may accumulate. If you’re shopping for such a display on the used market, you will recognize it by the faint, purplish reflection of room lights and daylight.

Lower-end CRTs use an etched glass tube face. It gives the glass a dull, non-specular appearance that helps cut down on glare, but such tubes do not provide the high contrast and color brilliance of tubes treated with an anti-reflection coating.

Flicker in CRT’s can cause headaches in some people when run at lower frequencies, so it may be ideal to pick a screen offering higher vertical refresh rates at whichever resolutions you intend to use. Most people who have problems with low frequencies (60 Hz) find it preferable to have at least 80 Hz at the intended resolution. Many won’t be bothered by this at all, however.

CRT displays and early LCD displays were developed at a time when television and computers used screens with 4:3 (width x height) aspect ratios. If your application requires a wide-screen display, even at the expense of reduced performance, a modern 16:9 aspect ratio LCD screen should be chosen instead.

Speakers
Computer loudspeaker sets come in two general varieties; 2/2.1 sets (over a wide range of quality), and “surround”, “theater”, or “gaming” sets with four or more speakers, which tend to be somewhat more expensive. A 2-speaker set is adequate for basic stereophonic sound. A 2.1-speaker set adds a sub-woofer to handle low frequencies. Low-end speakers can suffer from low bass response or inadequate amplification, both of which compromise sound quality. Powered speakers with separate sub-woofers usually cost only a little more and can sound much better. At the higher end, one should start to see features like standard audio cables (instead of manufacturer-specific ones), built in DACs, and a separate control box.

The surround sets include a sub-woofer, and two or more sets of smaller speakers. These support 5.1 or 7.1 standards that allow sound to be mixed not only left and right, as with standard stereo speakers, but front and back and even behind the listener. Movies and video games make use of this technology to provide a full-immersion experience. Make sure your sound hardware will support 5.1 or 7.1 before buying such a speaker system. If your budget allows, you can avoid the computer speaker market entirely and look into piecing together a set of higher-end parts. If you are buying a speaker system designed for PCs, research the systems beforehand so you can be certain of getting one that promises clarity rather than just raw power. Speaker power is usually measured in RMS Watts. However, some cheap speakers use a different measure, Peak Music Power Output (PMPO), which appears much higher.

Headphones can offer good sound much more cheaply than speakers, so if you are on a limited budget, but want maximum quality, they should be considered first. The advantage of headphones is that the acoustic environment between the audio driver is fully contained and controlled within the earcups and is not dependent on room acoustics. There are even headphones which promise surround-sound, though these have not been favorably reviewed.

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