1971: The first e-mail travels between two computers one meter apart. Many coworkers continue to communicate this way—rather than actually talking.
Credit: Getty Images
1979: Online services enter the scene, starting with CompuServe (1979), AOL (1983), and Prodigy (1984).
1980: The first dedicated chat room, CompuServe's CB Simulator, launches. Yes, as in CB radio.
1994: Anyone can make a website with Yahoo! GeoCities. (The service closed down in 2009.)
1995: Classmates.com emerges as a way to keep up with old high-school buddies. You probably saw the ads ("She married him?" "She's a model now?").
See also: Memory Lane.
1997: AOL Instant Messenger kills the chat room. Creepy middle-aged dudes everywhere mourn the loss.
1999: Anyone can blog! Open Diary, LiveJournal, and Blogger.com all launch at around the same time.
Courtesy of Flickr/jesseproper
March 2002: About 3 million people join Friendster during its first three months. But what to do with it once you have an account?
Courtesy of Flickr/ajkandy
May 2003: With very little fanfare, LinkedIn arrives on the scene.
September 2003: Myspace debuts with tons of customization tools that reveal the terrible design sensibility of the average person.
Courtesy of Gizmodo
February 2004: Mark Zuckerberg, the Harvard dropout with the Adidas shower sandals, follows up his success with Facemash (think: Hot or Not) by launching Facebook. Six years later, he's king of the world.
Also: Flickr launches.
December 2005: "Lazy Sunday," a music video featuring Andy Samberg and fellow cast member Chris Parnell is broadcast on Saturday Night Live and then goes viral. Going viral becomes a thing.
March 2006: Blogs are deemed too long. Twitter sets the new upper limit: 140 characters.
December 2006: Yahoo makes a billion-dollar bid for Facebook. No deal.
January 2007: Justin Bieber posts his first video—a shadowy Ne-Yo cover shot in a school auditorium—to YouTube. A gazillion views and counting.
February 2007: Twenty-year-old founder David Karp bills Tumblr as a blog for the lazy: "a fabulous alternative to the 90 percent of Web users who don't care to maintain a blog," he posts to WordPress.
Courtesy of Flickr/parawendolyne
July 2007: Regular folk submit questions for the candidates during the CNN-YouTube presidential debates. Anderson Cooper moderates.
April 2008: Facebook's traffic overtakes that of Myspace, which goes from being a massive social network to a place for bands to get the word out.
March 2009: The world gets thousands more mayors, thanks to Foursquare. And badges. Suddenly everyone wants a badge.
February 2010: Rumors suggest that Kim Kardashian earns $10,000 per endorsement tweet.
March 2010: Facebook beats out Google as the most trafficked site on the Internet.
October 2010: Instagram launches.
May 2011: LinkedIn has a famous initial public offering (IPO). Share prices more than double, and words like bubble and frothy market are bandied about.
June 2011: The masses learn the difference between a tweet and a direct message thanks to Anthony Weiner.
Justin Timberlake (perhaps inspired by his role as an Internet mogul in The Social Network) and Specific Media acquire Myspace for $35 million—$545 million less than News Corporation paid for it in 2005.
August 2011: Details magazine publishes "The Social Issue," guest edited by Ashton Kutcher. Okay, well, it was important to us.
November 2011: After a Joe Paterno-related flub on Twitter, Ashton Kutcher hands over the keys to @aplusk to his team. Twitter will never be the same.
January 2012: Google+ hits the 90-million-user mark and—experts predict—is on track to reach 400 million users by the end of the year, which would make it half the size of Facebook.