THE IDIOT'S GUIDE TO CYBERSPACE 2 e-MAIL

NOT so long ago, the essential badge of modernity was a fax number. Now, the line to have on a business card is an electronic mail address.

E-mail, as it is known, is well-established in America and is rapidly gaining ground in Europe. Before Christmas, the Today programme gave an e-mail address to which listeners could send their "personality of the year" suggestions. A sign of times to come.

Electronic mail has one huge advantage over phone calls - cost. A call to the US is expensive, especially in peak time. An e-mail message costs as little as a local phone call. A computer file - a work document, for example - is unlikely to cost more than 50p to send anywhere in the world.

But the main reason e-mail is spreading is simply because more people have the equipment to send and receive it. Anyone who has a computer and a "modem" can send letters to their more technologically advanced friends around the world.

Before being able to send e-mail (or indeed to gain access to any of the many services now available on computer), it is essential to sign up with an "on-line" company. There are a dozen of these available to British computer users. They range from CompuServe - the biggest in the business, with a huge range of services, including an encyclopaedia, travel information and electronic shopping - to small British companies that are simple gateways to the Internet.

The what? The Internet is a network of computers round the world. It was set up by the US Defence Department to allow military researchers to transfer information between their computers. But it is now believed to connect 25m people, because every subscriber to an on-line service can use the Internet to connect to subscribers to other services. It is thus the computer equivalent of a long-distance phone network, connecting all the national systems together; and its main use is as a conduit for e-mail.

It is worth getting a special computer disc from the on-line provider which makes your system as easy to use as possible. Instead of having to know the correct written computer commands, you can click your mouse on a pictogram or icon.

There's a monthly rental for the on-line service (anything from £6 to £20), which allows you send and receive a certain amount of electronic mail. Beyond that volume there is a small charge per message. The on-line company automatically charges your credit card account.

When you switch on your computer and select the "mail" icon, you will be told if there are messages waiting for you. You can read them, print them out, and send a message straight back by hitting the "reply" button. It will be sent automatically to your correspondent; you do not even have to look up the address. With some on-line systems you can build up your own phone directory which can be used like a memory on a telephone.

There two disadvantages to e-mail. First, if you do not know the e-mail address, it can be difficult to find it out. CompuServe has a directory of its members - but they are only a fraction of the entire e-mail population. The Internet needs a directory,but as no one owns it, it is unlikely to get one.

Second, electronic mail is not particularly secure; if you are sending top-secret plans, better stick to what technopeople call snail mail - Her Majesty's postal service.