Back in the days when the internet was still called Arpanet, a technician called Ray Tomlinson sent a message to other workers in his department saying that he had developed a kind of 'electronic mail'. This first email carried instructions how to use the system. Right from the beginning email used the system of user@computer which is still in use today.
Although it is now identified with email the @ symbol has a much longer history. It was originally used in business to show how much of something was available for a particular price. For example a businessman might offer to buy 500 widgets @ five pence each. Even today in British markets you can see signs like 'potatoes @ 50p per kilogram'. Now the @ means that the part in front is the name of the person with that address, and the second part is the name of the computer that receives his mail.
Not only email but every type of communication on the interent uses a system which everyone has agree on. These particular ways of doing things are called 'protocols'. There are two main protocols for email - one for sending mail and another for receiving it. You usually send mail from your personal computer using a protocol called SMTP which sounds complicated, but actually means 'Simple Mail Transfer Protocol'. Your email is not sent directly to the person you are writing to, but to a computer which that person can log into can get the mail when it suits him. This is like picking up mail from the post office, so the protocol for doing this is called POP or 'Post Office Protocol'.
It did not take long before some people realized that because sending email is free for the sender, it is possible to send advertisements by email to many people at very low cost. Spammers know that what they do damages the internet and often offends people, for example by advertising pornographic web sites, but if even 0.001% of people reply to their advertisements they can make a profit. As a result, about eight of every ten emails on the internet are spam. The name comes from a British comedy act where a group of men in a room start singing 'spam, spam, spam' and they get louder and louder until no-one else in the room can have a conversation.
Email is a less formal kind of letter. Sometimes people want to show that they are joking or smiling or angry or disgusted. This can be done by using punctuation to make little faces, though you have to look at them sideways to understand them. The most common ones are :-) happy, :-( sad ;-) winking :-s disgusted, :D laughing and not sure :-/
When you send an email, your address is added so that the person getting the email just has to click 'reply' to write back to you. However, people who use email to send spam or viruses by email do not want people to know who they are or they will be stopped. So they change their emails to make it look as if they were sent by someone else. This is why you might sometimes get a message saying that you emailed someone a message when you did not.
