Sometimes called Email. A way of sending and receiving messages between users on a network. If you work in an office and all the PCs are linked in a local area network, you could send messages to each user on the network. If you are connected to the Internet, you can send messages to any other user who is also connected to the Internet. In order to send a message, you'll need special software.


To imitate something else. For example, a special piece of software running on an Apple Macintosh can emulate Windows and allow you to run PC programs on a Mac.


A function or menu item that can be used. If you look at the software you are using, you'll sometimes see some of the options appear in grey rather than black. These are not enabled and you cannot use the option. For example, if you are using a word processor and have not selected an area of text, the Copy and Cut commands in the Edit menu are shown in grey and cannot be used. If you select an area of text, look at the Edit menu again and you'll see these options now appear in black and have been enabled.


The basis of network security. Encryption encodes network packets to prevent anyone except the intended recipient from accessing the data.

End user

The end user is you! You are the person who will use the program or product that a developer is creating.


The <

> key on your keyboard. Almost all commands used on a network should be followed by <

>. Also called <return>, <cr>, or carriage return.


The environment is the imaginary space in which you work when you use your PC. When you switch on your PC and it loads DOS or Windows, it creates an environment for you to work in. This can be changed to suit your needs- by defining its characteristics such as colour or wallpaper, and by setting up the printer, keyboard and fonts for you to use.

Error box or message

A small window that pops up to tell you an error has occurred. For example, if you have tried to do something that the program does not understand, or if an error has occurred in the program.

Error Checking

Uploading or downloading transfer check employed to identify errors in data transmission.

Esc key

A key on a PC keyboard, in the top left-hand corner, that is sometimes used to cancel an action. In Windows pressing the Esc key is the same as selecting the cancel button. If you press Alt-Esc within Windows you will cycle between any program windows that are currently running.


A standard and probably the most popular connection type for Local Area Networks (LANs). It was first developed by Xerox, and later refined by Digital, Intel and Xerox (see also DIX). In an Ethernet configuration, computers are connected by coaxial or twisted-pair cable where they contend for network access using a Carrier Sense Multiple Access with Collision Detection (CSMA/CD) paradigm. Ethernet can transfer information at up to 10 Megabit-per-second (Mb/s).

.EXE file

The three-letter filename extension that indicates that a file is a program and can be run. If you start a DOS window from Windows (or if you are already in DOS) type DIR and you'll see the names of all the files stored in the current directory on your hard disk. To the right of the filename is the three-letter filename extension that describes the type of file. DOC means document, WAV extension Wave or sound file, EXE means executable- a program file that can be run. To run a file with an EXE extension, just type in its name- you don't need to add the EXE suffix- and press Return.


A program that's supplied with Windows 95 that lets you manage all the files stored on a disk. With Explorer you can copy files, move files from one folder to another, create new folders, and rename or delete files and folders. Explorer can also view folders on other PCs in a network. To start Explorer, click on the Start button, then choose Programs/Explorer. Windows 3.1x users have a similar utility called File Manager that's in the Accessories group.


To convert a file from its native format to another format so that it can be read by a different program. For example, if you have written a letter in Microsoft Word and want to give it to a friend who uses a Word Perfect for Windows, you need to export the Word document to a Word Perfect format file using the File/Save As option in Word .


The three-letter code at the end of a filename that generally indicates the type of format of the file. For example, a filename in MS-DOS might be Letter 1 with the extension.doc. This is written with a full stop separating the two parts of the name. The three-letter extension,.doc, shows the files is a document. Similarly, .bmp means a bitmap file, .exe means an executable program file and so on. In DOS and Windows 3.1x, the length of the filename cannot exceed 11 characters. With a three-letter extension this leaves just eight characters for the filename. In Windows 95 this has been charged .