Electronic mail.
1. A service that sends messages on computers via local or global networks.
2. A message that you send or receive over the Internet, a phone line, or a company network.

Email is the trendy way to communicate in the 1990s. Email enables you to send and receive plain text, pictures, movies, music, almost anything you can think of that you can generate or load onto a computer. Many people prefer communicating by email to telephoning, sometimes because it takes less time to send an email message than to pick up and dial the telphone, sometimes because they may not want to disturb the other person for a short message, and sometimes because they may just not feel like talking!

From a user point of view, basic email is now straightforward. It is the bread-and-butter Internet application, for obvious reasons. It is:

• easy to use. The name@domain structure of the address is becoming standard, although a few systems, such as CompuServe, use an impersonal 9-digit number in place of a name.
• reliable. If a message does not get through, the sender usually receives an explanatory warning message.
• fast. In theory, it is almost instantaneous; in practice, a little slower.
• cheap. There are no materials costs - paper, envelope, etc. The actual cost of carriage - in terms of processing resources and electricity - is so trivial that it is virtually free at the point of use. (There are obviously hugely expensive infrastructures necessary, so the indirect cost is much higher).
• convenient. Most systems enable messages to be composed off-line, carbon copies sent, one-stop mail-shot with distribution to all addresses on a list, a copy saved for reference. Received messages may be forwarded without amendment or with comments appended or embedded. Some systems can notify the sender when the recipient reads the message.
• flexible. Adding attachments enables other documents to be included inside the "envelope". In a teaching environment, this means that a student can send an assignment written in Word, say, and which includes graphics and sound clips, to the course tutor as an attachment to a mail message.
• relatively secure. Legally, no one can read your email. In practice, the packets which make up the message could be intercepted and read at any of the network nodes across which they are routed. If security is paramount, the message may be encrypted. Sender and recipient must have access to the same encryption/decryption algorithms. For example, there is a strong encryption program in the public domain called PGP (Pretty Good Privacy), although governments - notably the US Government - are trying to challenge the legality of this.