Love it or hate it, Twitter has changed the way that 100 million of us - that's the number of active users, announced on 8 September - consume information. Hyperactive, quick to anger and brutally brief - a tweet can be no longer than 140 characters - the microblogging service has given us a slew of jargon, from "retweets" to "Twitterstorms", since its co-founder Jack Dorsey sent the first tweet to his seven followers in 2006. The service shows no sign of slowing down, claiming the scalps this year of cheating celebrities (through a superinjunction-busting account) . . . and of the cheating congressman Anthony Weiner (who accidentally posted a picture of himself in underwear to a public feed). At 34, Dorsey - now executive chairman - is worth an estimated $300m.
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