In modern times, people have communicated by letter, telegraph, and telephone. But no one method has become as widespread as quickly as the use of email. The first email message took place in 1971, and according to its sender, Ray Tomlinson, it was probably the following: "QWERTYUIOP." What was significant about that?
Nothing, really. This is just the top row of keys on an English-languages keyboard. Tomlinson was just testing out the system and using a nonsense message. He had no concept that he was going to start a revolution in communication
Tomlinson was one of a group of scientists who were working on developing better computers. The scientists at his site were able to send a message to a "mailbox " on the computer on their site. Other scientists could view the message in the mailbox. But there were other computers at other sites where scientists were working on the same project. Tomlinson's idea was to figure out a way to deliver message to mailboxes on those remote computers. He used @ sign to identify messages that were headed out of the local machine to the more distant ones. That was the start of emailing systems the we still use today.