Twitter goes back to the start for birthday

Twitter marked its eighth birthday by launching a new tool enabling users to look up their first tweet, and that of anyone who uses the social media site.

First-tweets.com allows users to type in the name of any Twitter account and find out what was the first tweet they posted. Since it launched in 2006, more than 240m people have joined the social network.

British prime minister David Cameron and US president Barack Obama are both prominent on Twitter.