Celebrities mark Twitter milestone
A host of celebrities have celebrated seven years of Twitter.
Sir Richard Branson, Gary Lineker and Robbie Williams were among tweeters who shared their thoughts about the social network.
The first ever tweet was sent in San Francisco, California, by Twitter creator Jack Dorsey on 21 March 2006.
Today, there are 200 million users worldwide, with 10 million active users in the UK alone, according to Twitter.
Journalist and author Kate Bussmann, who wrote A Twitter Year: 365 Days In 140 Characters, said: "It's no understatement to say that in seven short years, Twitter has changed the way the world communicates.
"It's given us all the power to get our voice heard and to connect easily and instantly with other people who care about the same things we do - whether that's politics or sport, Justin Bieber or Downton Abbey. It's made the world smaller."
Twitter allows users to post messages containing 140 characters or less, though 40% of users do not tweet but use the platform to follow other users.
Lineker (@GaryLineker), who has 1,475,000 followers, said: "I use Twitter for the knowledge, the news, the humour, the sport, the ability to eavesdrop on the great and the good, and above all, for the nonsense."
Sir Richard (@Richardbranson), who has more than three million followers, said: "To me, Twitter means a way to communicate with people in real-time, highlight good causes and - above all - have fun!"
Celebrities also recommended their favourite people to follow, with Lineker suggesting Piers Morgan, and sports presenter Jake Humphrey and Top Gear host Richard Hammond both recommending Canadian astronaut Chris Hadfield who tweets updates and images from the International Space Station.