It's a sad day for the Internet: Ray Tomlinson, widely credited with inventing email as we know it, has died from a suspected heart attack at 74. In 1971, he established the first networked email system on ARPANET (the internet's ancestor), using the familiar user@host format that's still in use today. It wasn't until 1977 that his approach became a standard, and years more before it emerged victorious, but it's safe to say that communication hasn't been the same ever since. When's the last time you sent a physical letter?
In some ways, Tomlinson also changed language itself. His choice of the @ symbol for email popularized a once-niche character, making it synonymous with all things internet. Arguably, he paved the way for modern social networks in the process. Twitter would be a very, very different place without the @ mentions that help you chat with other users, and numerous other services use it as an easy way to share status updates.
Tomlinson received his share of formal recognition. He's a cornerstone of the Internet Hall of Fame, and he received everything from a Webby Award to a Prince of Asturias Laureate. However, he almost doesn't need those. Much like fellow internet pioneers Tim Berners-Lee or Vint Cerf, you're encountering his legacy virtually every time you hop online. And barring a sea change in communication, it's likely that the effect of his work will be felt for decades to come.