Ray Tomlinson, the inventor and sender of the very first email, has died.
Before its invention in 1971 there were basic messaging systems, but no way to send a message to a specific person using a different machine.
With so few computers on the recently invented ARPANET, the precursor to today's internet, Mr Tomlinson says there was no pressing need for email – it just "seemed like a neat idea".
Using the @ symbol to separate a person's username from the email host was also his idea, chosen because it was rarely used.
Google's email service, Gmail, paid tribute to Mr Tomlinson on Twitter.
The content of the first email, sent between two computers sitting next to each other, was "completely forgettable… and therefore forgotten", he said in 2009.
Reports say Mr Tomlinson, 74, died of a heart attack.