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Definitions and Walkthroughs
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Acceptable Use Policy

Acceptable Use Policies (AUP's) generally prohibit certain types of undesirable use on a computer system/service not owned/managed by you, i.e. University, Workplace, ISP etc. It may be the case that the AUP specifically prescribes what the computer system/service is to be used for, and prohibits activity not stated.

Often, it will be a condition of use that you agree to abide by a fair use policy; in many cases, the user will need to agree to the terms in writing, or by an electronic form before access is given.

Common restrictions include (but are not limited to);

  • No pornographic or offensive material
  • No copyright infringement
  • No creation of defamatory material
  • No activity that may cause damage to the computer system/service
  • No illegal activity
  • No commercial activity
  • Do not share login details


ActiveX is a browser add on created by Microsoft that allows dynamic applications to install and run in Internet Explorer, similar to the Java applet. They can enhance your browsing experience by allowing animation or they can help with tasks such as installing security updates and Microsoft Update.

Adobe Flash player

Adobe Flash player is a browser plugin that allows you to view and interact with various forms of multimedia on the web, such as games, animations, and videos. Flash is necessary for a number of in-browser applications, including BBC iPlayer and YouTube, and if you are having trouble using one of these services, you might need to install or re-install the plugin.

Adobe Shockwave player

Adobe Shockwave player is a browser plugin that allows you to view and interact with various forms of multimedia on the web, such as games, animations, and videos. Shockwave is necessary for a number of in-browser applications, and if you are having trouble watching a video or playing a game, you might need to install or re-install the plugin.


Asymmetric digital subscriber line (ADSL) is a form of digital data transmission, a data communications technology that enables faster data transmission over copper telephone lines than dial up.


See here.


See here.


An applet is any small application that performs one specific task; sometimes running within the context a larger program perhaps as a plugin.


See Acceptable Use Policy



A backup involves creating copies of data so that the additional copies can be stored elsewhere such as a CD/DVD or an external hard drive (long term, permanent storage). This is done so that your data is not lost if your computer goes kaputt for whatever reason.

  • A USB pen drive would not be recommended for storage as it can easily be corrupted. However it can be used to transfer data.


Bandwidth, without going into how it works in principle, is a term used to measure how much data can be transmitted over a particular medium in a given time period. Most people's experience with bandwidth is in internet communications, where the speed of your connection is measured in kbps (kilobits per second) or Mbps (Megabits per second).

The higher the bandwidth, the more data you can transmit and receive.

Most internet service providers (ISP's) advertise "upto 8Mbps" packages. Your actual bandwidth depends on a number of factors, chiefly with ADSL over a BT line, the distance from the exchange. Typically (across the UK), an "upto 8Mbps" package will give you 3.6Mbps. [1]

It is worth noting that bandwidth is usually measured in bits per second (often with a prefix like kilo or Mega). Your computer will report download speeds in bytes per second. Therefore, theoretically speaking, a connection with 1 Megabit per second (1Mbps) will deliver a maximum download speed of 125kB/s as there are 8 bits in a byte. Note the lower case "b" for bits and the upper case "B" for bytes - this notation is very confusing, and misleading if you do not look carefully.


An acronym of Basic Input Output System. When the computer first powers on, the BIOS software runs, and checks memory, starts CD/DVD and hard drive(s) start running, and then continues to load the operating system (presuming the hard drive/other bootable media has an operating system to run).


Blu-ray is a high definition video format which is the successor to DVD. To watch a film on a blu-ray disc, you will need an HD TV and a blu-ray player. Some computers and laptops will come with blu-ray drives, or as an option. Blu-ray is commonly mispelled as blue-ray.

Blue Screen of Death

See here.

Further reading here.


Bluetooth is a wireless protocol that allows data transmission over short distance, typically < 100m.

Boot disk

A boot disk is a storage media (such as CD/DVD) which a computer can load/run either an operating system or a utility program on start up.


Burn refers to the process of recording data onto a CD, DVD or Blu-ray disk.



Cache is a temporary storage of frequently accessed data stored for quicker access. For example, if you open up a program and then close it again, then 2nd time you open it, you should find that it's quicker load. You can find cache memory in processors and hard drives, typically measured in MB (megabyte).


A codec can be hardware or software, which converts a digital signal to audio or video. For example, if you have an MP3 (a compressed music file), then a codec converts the digital signals into audio. Without the codec, the computer would have no idea what to do with the MP3 file, and wouldn't be able play it. Digital Set Top Boxes (such as Freeview) contain a codec to decode the digital signal received via the aerial. A codec can also be used to convert an analogue signal into digital form for storage or transmission.


The basic idea of compression is to take a file, and reduce the amount of space that it takes up. This can be useful for sending files over e-mails, uploading to the internet, or many other uses. To compress a file, the computer looks at what is repeated, and stores information about the repetitions, instead of the repetitions themselves. So if you have a large number of 0's, uncompressed you may have '00000000000000000000', but you could then compress that to '20x0'. The compressed version then takes up a fith of the space used by the original, and can be expanded again to the original form. Video compression works by looking at the changes between the previous frame and the current frame, and only storing the change. So if, for example, the background image doesn't change between frame 1 and 2, then the background information from frame 2 can be discarded, as it's the same as in frame 1. Compressed files are commonly stored in .ZIP (WinZip) format, but .RAR (WinRAR) is not uncommon. The higher the level of compression, the longer it takes to compress (typically).

Control Panel

On Windows PCs, the Control Panel provides access to settings for that particular computer.


An internet cookie keeps track of basically everything you have done on the web - usernames, log in names, website preferences, shopping carts....


The Central Processing Unit carries out instructions for the computer. They simple fetch, decode, then execute instructions. The 2 main manufacturers are Intel and AMD. When looking at new computers, things to look out for:

  • Clock speed - The number of instructions the CPU process per second (measured in gigahertz [GHz]). The higher the better.
  • Number of cores - Since clock speeds cannot keep increasing, manufacturers add more cores (e.g. dual or quad core). The more cores the better. Note that having more cores doesn't mean you multiply the clock speed by the number of cores i.e. an Intel Core 2 Quad Q8300 @ 2.50 GHz does not equal to 4x2.5GHz!
  • Cache - A small section of the processor for quick access to data (measured in megabytes [MB]). The larger the better.
  • FSB - This is the bus that carries data between the CPU and the northbridge. The frequency at which a processor (CPU) operates is determined by multiplying the clock multiplier by the FSB speed.
  • Socket - Each line of processors will have a different socket that it plugs into the motherboard e.g. Intel's socket 775 or AMD's AM2/AM3. The processor and motherboard have to have the same socket to work.



In terms of computers, data is stored on the hard disc drive, and is all the information to do with computer. For example, Word Documents, E-Mails, Programs, Music, Videos, Settings and Pictures are all examples of data. It is stored in bits (1's and 0's) and can be moved around the computer at very high speeds. A 700MB video consists of approx 5,872,025,600 bits (700MB x 1024 (KB) x 1024 (Bytes) x 8 (Bits)). A typical hard drive on a new computer may be 500GB (which is 4 x10^12 bits - bearing in mind that HDD manufacturers define 1KB as 1000 Bytes, not 1024).

Denial of Service

A Denial of Service (DoS) attack intends to make a website server unavailable to other users. This is acheived by sending a huge number of connection requests at the same time to the server, making it very busy, and unavailable to normal users.

Digital Rights Management

Digital Rights Management (DRM) is a method of preventing digital content from being shared between users. A common use of DRM is when downloading music from the internet. To prevent the user from playing the music on more than their own computer/portable music player, the file may be encrypted with information about the computer/devices that it can be played on, and if it is attempted to be played using a different device, it won't work!




Disk Operating System. Perhaps one of the most basic operating systems. DOS uses a CLI (command line interface), meaning commands need to be entered at the command prompt for tasks to be performed.

  • thomasw234: I wouldn't say that DOS is a basic operating system, it just lacks the user interface that Windows has, and therefore appears more simple. To get it up and running with all the software you want can be quite difficult due to the 640KB conventional memory limit!


See Denial of Service


A driver is a piece of software that tells the operating system how to interface with a piece of hardware (typically). For example, if you buy a new printer, you first should install the drivers for the printer, usually provided on a CD. Then, when you plug in the printer, the operating system can setup the printer, and send documents and pictures to it.

  • spikeymike: Any hardware will not work without drivers, just like a car, it cannot operate without a driver.


See Digital Rights Management



Encryption is the process of 'scrambling' a message to prevent unintentional viewers of data from being able to understand it. One of the most basic forms of encryption is to swap letters around. For example:



If I take the top row as the original letters, and the bottom row as the new letters, then I can translate 'HELLO' into 'SVOOL'.

'SVOOL' is now the encrypted message, and can be transmitted to another person who will know how to decrypt the messge (i.e. convert 'SVOOL' back into 'HELLO'). Please note - real life encryption is significantly harder to decrypt than this!

Executable File

An executable file causes a computer to perform indicated tasks according to encoded instructions.



File Allocation Table

Fair Use Policies

Fair Use Policies (FUP's) are a service provider's way of adding limits to "unlimited" service packages.

Common examples of where FUP's are used:

  • Mobile Phone Contracts
    • Often deals involving unlimited free texts/web browsing are subject to such clauses. Exceeding the limits of the FUP may incur additional costs, or your service may be degraded as a result.
  • Broadband
    • Unlimited broadband packages are often subject to FUP's. Exceeding your ISP's FUP may cause you to be moved up to a higher priced package, or cause your bandwidth to be throttled to a much lower than normal speed. If you repeatedly exceed the FUP, some ISP's reserve the right to slow your connection down to almost dial-up speeds.

File server

A File Server is a machine that sits on a network, whose purpose is to store user data. Whilst file servers are commonly found in the corporate environment, they're becoming increasingly important in the digital home. They are a convenient way of storing data (such as documents, music and videos) on one machine, then streaming that data to the device that requires it, on-demand.


A Firewall is a device that defends a network from remote attacks. There are two types of firewall:

  • Software firewalls
  • Hardware firewalls

Most people these days will connect to the internet through a router. Consumer routers generally have hardware firewalls built in. Most people will also have a software firewall, built into their operating system, or a third party solution like Zonealarm. More suggestions for software firewalls can be found here.

Firewalls inspect data coming in from the internet and decide whether it's legitimate traffic, or whether it could be an attack on the network. If it's legitimate, it lets the data pass through. If it's not, the firewall discards the data and does not let it pass.

You should always protect a Local Area Network with a firewall of some sorts.


See Adobe Flash player


Graphics card


See Graphical user interface

Graphical user interface


Hard disk

The part of a Personal Computer (PC) that stores information. Traditional hard drives use magnetism to store data but more modern Solid State Drives (SSDs) have no moving internal components. Hard drives come in various speeds, most desktops HDDs are 5,400, 7,200 or 10,000rpm, laptops are normally 5,400rpm.


Your computer consists of many pieces of physical hardware. In a desktop PC, you can quite easily upgrade some of the components to improve the performance. In a laptop, only the RAM and hard drive can be changed easily.


Internet service provider

IP address


See Internet service provider







See Local Area Network

Local Area Network


MAC address

A Media Access Control address is a unique address assigned to a networking interface card. There are 2^48 or 281,474,976,710,656 possible addresses.


A Macro is a script, or sequence of actions that are embedded into things like Word documents to allow the user to perform repetitive or lengthy tasks by carrying out a much shorter operation, such as a keystroke, or mouse click. You should only use macros from trusted sources, though. Macros can be written to be malicious as well as helpful!



An Acronym of 'Mega bits per second'. Is a measure of the numbers of bits (1's and 0's) can be transferred per second. Quite frequently confused with MBps, MegaBytes and other variations. MBps is the number of Bytes per second (a group of 8 1's and 0's) that can be transferred.






A group of computers that are connected together to share information/data.

There are many different types of network:

  • Local area network
  • Wide area network
  • Virtual private network
  • Intranet
  • Extranet
  • Internet

Network interface card


See Network interface card



See Optical character recognition


See Original equipment manufacturer

Operating system

The interface between the user and the hardware. Operating systems can be split vaguely into 3 areas: Microsoft Windows, Mac OS X and Linux.

Windows OS's you may see are 7 (released Oct 09), Vista (released Jan 07) and also XP. Most new computers will ship with 7, although some older models may still have Vista/XP.

Linux comes in many distributions (such as Ubuntu and CentOS) and are free alternatives to Windows.

Optical character recognition

Original equipment manufacturer


See Operating system



An abbreviation of "Peer-to-peer", which is a form of distributed computing in which several computers ("peers") connect directly to each other without any central coordination (e.g., from a server). This is most commonly referred to in the context of file transfer, where P2P networks allow for users to download/upload files directly from/to other users. There are several such file transfer networks, perhaps the most common of which involves the use of Torrent files.



Proxy server





Shuts down the computer, then starts it up again. Restarts are sometimes required after installing programs and updates, so that they install properly and start running. NOTE: this is not the same as reformat/reinstall




The networking device between your home and the internet. Its purpose is to route packets across the internet. There are 2 main types of router: ADSL/modem and Cable. Virgin Media are cable and pretty much everyone else is ADSL. ADSL modems connect via the phone line. Note that an ADSL router will not work with Virgin Media's cable service, and vice versa.


Safe mode

Safe mode is diagnostic mode of Windows that you can boot into to help troubleshoot problems.

Safe mode is different to how you normally boot Windows in a number of ways. Firstly, it doesn't automatically run any programs on boot, which means that any viruses that run as soon as you start up your computer normally will not be able to run. Secondly, it disabled most device drivers, which could be causing incompatibility issues. Safe mode also uses very basic graphics, which means problems with your graphics card are ignored for the time being.

To boot into safe mode, tap F8 a few seconds after you start up your computer (before the Windows logo appears). If you multi-boot several partitions, tap F8 when the boot menu appears. Note that if you will need to choose "safe mode with networking" if you wish to connect to the Internet whilst in safe mode.

Some older computers use a different key to enter the advanced boot options. It will normally be F8, but you may find that this doesn't work. If you're sure that you've tried to press F8 at the right time, you could also try pressing Esc, Delete, F5, or another function key (although the latter might bring up unwanted options, in which case just turn the computer off again).

Once you are in safe mode, there are several things you could try to get your computer back to working order. Firstly, safe mode should give you access to system restore, which may be able to restore your system back to a time where the problem was not present. If you suspect a recent hardware addition/change is causing the problem, you can go to the control panel and uninstall the driver for that device.

Remember, safe mode does not fix problems, it merely offers a way of booting into Windows so you can carry out the necessary diagnostics.



See Adobe Shockwave player


Sound card



System tray

The notification area, often incorrectly called the system tray, is a section of the taskbar that provides notifications and statuses.



The taskbar is the bar that is usually situated across the bottom of the screen. It contains the start button, quick launch buttons, and the system tray. windowstaskbars2.png







A virus is a malicious piece of software, often designed to maliciously corrupt data. It is so-called because of its ability to replicate itself and spread. Viruses more than often spread through the Internet, and can often be downloaded without the user knowing. Sources of viruses include P2P sharing, keygens, cracks, patches, malicious links, and programs imitating legitimate software such as anti-virus applications. If you think you have a virus, there are resources here and here that should help you through the process of isolating the virus and removing it.



See Wide area network

Wide area network







IEEE 802.11 is an international standard that provides the specifications for Wireless Local Area Networks (WiFi). You'll commonly see it on wireless network hardware, along with a letter (sometimes referred to as the "flavour") after it; usually b, g or n - e.g. 802.11g

  • 802.11b
    • 11mbps
    • Legacy standard
  • 802.11g
    • 54mbps (up to 125mbps with some hardware)
    • De facto WiFi standard - most commonly used, around the world.
    • Pretty ubiquitous - almost all wireless networking hardware on the market supports 802.11g
  • 802.11n
    • Up to 144mbps
    • Newest standard
    • Requires special 802.11n hardware
    • Bigger range
More info: Wikipedia Article
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