For amplifying the global dialogue
01 The X Factor, aka Simon Cowell's post-Idol singing competition, was the first TV show to allow live voting via Twitter.
06 Ashton Kutcher turned over his account to his social-media company after a mistakenly sympathetic Joe Paterno tweet.
07 Japan's devastating 8.9-magnitude earthquake inspired a worldwide response of more than 1,200 tweets per minute.
08 Hashtag games like LessInterestingBooks can clog your feed, necessitating products like Slipstream to hide tweets.
13 Tiger blood, coined by Charlie Sheen during his meltdown, was 2011's second-most-popular hashtag. (No. 1? Egypt.)
14 Alec Baldwin deactivated his account following tweets about being kicked off a plane for playing Words With Friends.
17 OWS (short for Occupy Wall Street, of course). Protesters used Twitter to relay information about marches and raids.
18 AddACommaToAMovie was a hashtag game started by an L.A.-based TV writer. "The only downside," he later blogged, "is that you realize how many other funny people there are."
21 January 25, the start date of the Egyptian revolution, became a symbolic hashtag for its coverage and conversation.
23 Burberry premiered its spring/summer 2012 looks on Twitter, seconds before models hit the runway.
24 Sohaib Athar unknowingly live-tweeted the raid on Osama bin Laden's compound, proving yet again that news breaks first on Twitter.
02 ThingsThatPissMeOff is the type of evergreen meme that develops a common language among Twitter's 200 million users.
03 Barack Obama began personally tweeting last June. Later, he announced the end of the Iraq war in less than 140 characters.
04 Steve Jobs was Twitter's most-talked-about person last year.
05 McLobster, offered for a limited time at several New England locations, was rumored to be getting a national rollout.
09 NewNew is the nickname for Twitter's "fly" interface launched in December, the brainchild of Twitter chairman Jack Dorsey.
10 The TreatItFwd promotion by Wendy's raised $50,000 for foster care by pledging 50 cents for every retweet.
11 Humblebrag commemorates those cringe-inducing updates from people for whom self-awareness is a foreign language.
12 Kevin Durant, the all-star Oklahoma City Thunder forward (@KDTrey5), kept fans happy during the NBA lockout.
14 Anthony Weiner torpedoed his political career--and pioneered the always-lame "My account got hacked" defense.
15 WorstXmasGift is a Jimmy Fallon--inspired hashtag segment that engages his fans on Twitter and on NBC.
16 Rebecca Black trended for weeks after her captivatingly literal music video "Friday."
19 Lady Gaga fans got #BornThisWayLyrics trending in advance of her single's release.
20 The Dallas Cowboys was last year's most-talked-about pigskin topic, despite--or because of--their maddening mediocrity.
22 Jong-Il: The North Korean dictator's death was largely mocked on Twitter with quips like, "Kim Jong Il? More like Kim Jong Dead."