Ray Tomlinson died March 5

If there’s a single symbol that represents the Internet Age, it’s the “@” sign. The second it makes its appearance in a string of text, our brains instantly recognize there’s something digital at hand, whether it be an email address, Twitter username or chat handle.
But there’s nothing innate about “@” that screams “computer.” In fact, it’s hundreds of years old, provided you believe a researcher who traced it back to 16th century Italian merchants. Then and afterwards, the symbol was largely used to indicate now-obsolete units of weight and other metrics. It was just important enough to appear on typewriters and, later, keyboards.
Then came a man named Ray Tomlinson came along.
Back in 1971, Tomlinson, who died on Saturday, was an engineer at a Boston firm that was experimenting with ARPANET, the forerunner to today’s Internet. His task: Create a way for ARPANET’s users, mostly academics and researchers, to send direct messages to one another, like a form of electronic mail. He soon reached his goal, forever cementing his status as the father of email. (You can either thank or loathe him for his creation, depending on how much of a mess your inbox is.)
But Tomlinson didn’t just create a new communications medium. He also gave a significant gift to our cultural lexicon, rescuing the “@” from disuse.
The story goes like this: While creating that early form of email, Tomlinson needed a way to separate users’ names from the names of their computers. He told NPR in 2009 that the “@” was perfect for two reasons. First, it lacked the baggage of other symbols on the keyboard, all of which carried their own preexisting connotations. Second, it was linguistically logical — typing “Alex at TIME” is a sensible way to fire off a message to somebody named Alex who works at TIME Magazine.
Today, the @ sign is finding renewed life outside of our inboxes. Most famously, Twitter uses it at the beginning of users’ handles, borrowing a convention from other chat software. The booming office communications platform Slack uses it in this way, too. And its significance has been recognized by the design world, with the Museum of Modern Art adding it to its collection back in 2010. It’s doubtful that email will die any time soon. But if it ever does, Tomlinson’s typographic contribution will certainly live on.