Binary code: A computer cannot understand instructions in what we would recognise as writing. Our programs have to first be converted (using a special piece of software called a compiler or interpreter) into a form that the computer can process. This form is binary notation and it is used for storing computer programs and data.

Binary notation uses only two digits: 0 and l, compared to the ten digits in decimal notation, or many characters in a spoken language, like English. However, these two digits can be combined to form infinite variations of numbers, and codes, which are used to convey messages to the computer.

Computers are powered by electro-magnetism. Regardless of the voltage, an electrical current within the computer, or a section of computer disk or CD-ROM, is either ON or OFF, or magnetised or not magnetised, or up or down, etc. Because of this two-state principle of electro-magnetism, computers can "read" the on/off messages of binary codes.

In decimal notation, we recognise the value of the number 215, almost without thinking, The last digit, 5, designates the number of single units, the next digit, l, the number of tens and the first digit, 2, the number of hundreds. More digits to the left indicate ten times the value of the digit to the right: thousands, tens of thousands, etc.

In binary notation, the far right digit, as with decimals, denotes the number of single units. The next digit from the right denotes the number of twos, the next the number of fours, eights, sixteens, thirty-twos, sixty-fours, one-hundred-and-twenty-eights, and so on. So, the decimal number 215 would be expressed, in binary notation, as:

1 1 0 1 0 1 1 1

Reading from the left, there is one 128, one 64, no 32, one 16, no 8, one 4, one 2 and one 1.

128+64+16+4+2+1= 215. This is fine for recording numbers; to record letters the computer simply uses numbers in a pre-defined code. The computer program will have stated that the next series of binary numbers will, in fact, be representing letters, eg 1 for a, 2 (or 10 in binary) for b, and so on.

Browser: Software which enables the user to view WWW pages, as you are at present. The browser displays documents formatted using html, which, by using hypertext and other techniques enables complex connections to other documents via the Internet. This inter-connectivity gives the Web its name. The most popular commercial browswers are, currently, Netscape's Navigator and Communicator and Microsoft's Internet Explorer.

Bulletin Board System: Forerunner of the Internet, BBSs enabled a wide range of remote computers to connect to central computers. These were often painfully slow but did permit a form of email and the downloading of files, often software "patches" and support information.

CD-ROM: Compact Disk Read Only Memory.

Client: An individual computer that uses a server to provide it with software and storage facilities.

Digital: The concept of conveying information using codes (usually in binary form) rather than by analogous methods, like varying electric currents, or vibrations in a vinyl audio disk, or photographic film.

Domain Name: The address of a particular web server - the first part of a URL. For example: www.wolffsys.co.uk is Wolff Systems' domain name. Technically, the full address is http://www.wolffsys.co.uk, but modern browsers insert the http:// (which stands for Hyper-Text Transfer Protocol) automatically.

After the company or organisation name, "wolffsys" in this case, comes a description of the organisation. Wolff Systems use the ".co" suffix, because it is a commercial company. International and United States companies use ".com" on its own. Other options are ".edu" for universities and colleges, ".gov" for government bodies, including your local council, and ".org" for other, usually non-profit-making, organisations and charities. Apart from the USA, the country code, ".uk" for the United Kingdom, comes last.

Entering the domain name into your browser will usually find the top-level index for that site. Sometimes, though, an address will be further refined. The BBC site, for example, may quote an address for access to a particular program, eg www.bbc.co.uk/eastenders, which allows you to skip the home pages of the site and go straight to the page for the popular Eastenders "soap". Anything after the forward slash is reference to a specific file, or directory, within the domain. Sometimes, the page you want can be a few directories "down" from the main server address. If you want a weather forecast for the Caribbean, for example, you can find it in

http://weather.yahoo.com/graphics/outlook/caribbean48.html.

The actual file is caribbean48.html, but this is stored in the directory, /outlook, which, in turn is a sub-directory of /graphics.

When no file is specified, the browser will automatically look for a file called index.html, which should be at the highest level of all sites. Therefore, typing:

www.wolffsys.co.uk

is exactly the same as typing:

www.wolfsys.co.uk/index.html.

Download: Both a verb and a noun, download is really another word for "copy", usually applied to the process of copying software (or data) from another area of the Internet. See also upload.

E-commerce: The growth area of the early 21st century. The ability to conduct commerce (more than simply buy-and-sell, also banking, investing, consultancy, etc.) via the Internet.

Email: Electronic mail. The ability to send a message in computer file form from one individual computer user to one or more other computer users.

Favorite Places: Web browsers have an option to store frequently-used or otherwise interesting sites in a list which can be used instead of typing in the URL every time. Sometimes called Bookmarks.

Hyper-Text Mark-up Language (html): The medium by which WWW pages are formatted. Using html, pages can be viewed across a range of computers. To see the actual hyper-text behind a page, click the right mouse button, or click on View at the top of the screen, then select Source, or View Source.

Hyper-link: The method by which hyper-text connects a point in one document to another position in the same page, another page in the same site or even another document somewhere else in the WWW.

ISDN: Integrated Services Digital Network. Transmission medium not requiring a modem which can convey multimedia elements.

Internet Service Provider (ISP): As the Internet is a "network of networks" it is necessary to become part of a network which is linked to the Internet. Large companies and organisations have this kind of infrastructure in place but individuals and smaller companies need an ISP to provide them with a suitable network. Rather than remain connected permanently, it is cheaper to go on-line only when email needs to be sent or the WWW accessed. The ISP remains permanently connected to the Internet so that it can store email which is passed on whenever an account-holder connects.

Modem: Acronym for MOdulator/DEModulator. Device that converts digital information into analog form, and vice versa, so that it can be transmitted via a telephone line.

Multimedia: Equipment and communication lines capable of carrying a variety of elements such as data, voice, video, and audio.

On-line/off-line: When a client is connected to a server and is communicating with it in some way, it is on-line. When the connection is broken it is "off-line". Sometimes activities can be performed (writing an email message, for example) off-line, going on-line just long enough to send the message.

Search Engine: As the number of web pages increase, the chances of finding what you actually want decrease proportionally. A seach engine (or search tool) is a web page which allows you to input one or more key words and then searches for matching sites. You will learn to refine your search otherwise you tend to end up with thousands of matches. The most popular search engine is Google, although there are others.

Server: Hardware, with associated software, which receives, processes, and replies to a query from a client.

"Spam": Unrequested junk email. Usually harmless but could propogate viruses. After a while you'll recognise and delete spam without even reading it, but it can be annoying. It is possible to reduce spam significantly by various filtering techniques, or by using commercial anti-spammer utilities.

Spreadsheet: One of the first, and most useful, application programs to be used on PCs, a spreadsheet is a computerised representation of a huge piece of paper divided into rows and columns. Text, numbers and formulae can be input to any of the cells. Columns and rows can be automatically totalled, carried forward to the next column, etc. Spreadsheets can be used for quite complex tasks, and are ideal for financial analyses, projections and repetitive mathematical calculations.

TCP/IP: Transmission Control Procedure/Internet Protocol. The heart of the Internet, used since the very beginning to enable one network, of virtually any type of architecture, to communicate with any other. Crucially, if any part of a TCP/IP internetwork fails, the rest of the internetwork can continue to run.

Upload: Usually applied to the process of copying web pages or other data to the Internet for storage on a server.

Uniform Resource Locator (URL): This is the "address" of a web site, and, by now, most people must be familiar with the format of these locators. It seems that almost every advert, radio and television program and many company letterheads have the familiar "www.mycompany.co.uk" discretely positioned. Actually, web site addresses consist of numbers. When someone types "www.wolffsys.co.uk" into their browser, the Internet looks up the address in a reference table to see where it is currently located, then finds the best way to access that location.

Virus: A computer virus is simply a small program which can be hidden inside an otherwise harmless-looking file and, when copied to a computer, cause some malfunction to occur. This can range from an annoying but harmless message to rendering the whole computer inoperable, necessitating re-formatting of the hard disk and lost data. The Internet is an ideal distribution medium for viruses. Typically viruses are received in files attached to email (not the email messages themselves) or Internet downloads. If you receive email from an unknown source, inviting you to open up an attached files, be very wary. It is probably aways best to delete them without reading. There are many virus detection programs available, which check files as they are downloaded.

WWW: The World Wide Web, or, sometimes, just "The Web".