Twitter's top 2011 hashtags: #egypt and #tigerblood Published duration 8 March 2012

image caption Tweeters showed interest in the Arab Spring

The most popular hashtags of 2011 have been revealed, illustrating how Twitter spans diverse topics from politics to celebrity gossip.

Hashtags are used to group together tweets relating to the same subject.

Top of the list was #egypt, followed by #tigerblood.

The first refers to the unrest in Egypt during the spring of 2011 while the second references a comment made by actor Charlie Sheen, following his sacking from a hit US comedy.

Sheen made the headlines in 2011 for a series of often rambling public rants which culminated with the comment to online celebrity gossip site RadarOnline: "My fangs are dripping tiger blood."

At the same time, he joined Twitter and racked up one million followers in the first 24 hours, believed to be a record for the site.

He used the site to comment on the dispute between him and the Two And A Half Men show's producers, at one point tweeting: "I'm looking to hire a #winning INTERN with #TigerBlood."

Twitter also released details about the hottest topics in a range of subjects, including the most talked about actors, countries and news topics.

The resignation of Egypt's President Hosni Mubarak, which triggered a series of uprising across the Middle East and Africa, topped the news list, followed by the US special force's fatal raid on Osama bin Laden's home. The Japanese earthquake and tsunami ranked in third place.

In the food category the McLobster took top place after it trended on rumours that fast food chain McDonald's was to roll out the crustacean-based sandwich across the US. Previously it had only been available in Canada.

A teenager who was unknown at the start of the year topped the music list. Would-be popstar Rebecca Black was propelled into stardom when her debut single Friday was released on YouTube to widespread mockery. At the time of its release, the song ranked top in global trending topics on Twitter, surpassing the Japanese earthquake crisis.

Perhaps surprisingly teen hit Justin Bieber did not feature in the top names.

As well as featuring in the top hashtags, Charlie Sheen's off-screen antics also moved him to the top of the most talked-about actors

British talent in the top 10 including Ricky Gervais, off the back of his controversial Golden Globes appearance, Colin Firth, who won the best actor Oscar for his performance as King George VI in The King's Speech and Pete Postelthwaite, a British character actor who died in 2011.

"Among other things, we saw history unfold in the Middle East, mourned the passing of Elizabeth Taylor, celebrated National Whipped Cream Day, and cheered for the Dallas Mavericks, Texas Rangers and Wayne Rooney," Twitter said in its official blog