Ray Tomlinson

Mail between users of the same time-sharing computer already existed. Working at BBN on the TENEX operating system, Tomlinson combined the mail program SNDMSG with the file-transfer program CPYNET so that a message could be written into a mailbox on a different machine across ARPANET. Separating the user name from the host name needed a character that never appeared in names. The @ was on the keyboard and already meant "at".

He couldn't remember what the test message said — probably something like QWERTYUIOP. He described the whole thing as a fairly simple job and was puzzled for years by people wanting to interview him about it. Email nonetheless became the network's first genuinely popular application.