Twitter at 10: A timeline of its biggest moments

Twitter marks its tenth anniversary on Monday, with the social media site having hosted some of the biggest social movements of the last 10 years.

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Five hundred million tweets are now sent every day, with 200 billion posted every year and hashtags such as #JeSuisParis in the wake of the November terrorist attacks in the French capital dominating international debate online.Here are some of the tweets that defined it:

2006 – The first tweet

Co-founder Jack Dorsey Tweeted first, when the service was called "Twttr."

2007 – The hashtag appears

Early user Chris Messina proposed the use of a hashtag to denote people at the same live event.

2008 – Ice on Mars

When the Mars Phoenix Lander found ice on Mars, NASA used Twitter to break the news.

2009 – Plane on the Hudson

Early user Janis Krums happened to be on a ferry when a plane went down in the Hudson River.

2010 – Royal engagement

In a royal first, Clarence House, the Prince of Wales' private office, created a Twitter account to announce Prince William's engagement to Kate Middleton.

2011 – Bin Laden raid

Up late one night, Sohaib Athar inadvertently live-tweeted the raid on Osama bin Laden's compound in Pakistan.

2012 – Obama's second term

Before he appeared publicly to affirm his second presidential win, President Obama noted it on Twitter. And within hours it became the most retweeted for the year.

2013 – Boston Marathon

Two bombs shook the Boston Marathon – and the world. As news of the blasts and the manhunt spread, Twitter became crucial for journalists, police and citizens alike.

2014 – Fighting terror

The #BringBackOurGirls movement was created when more than 250 schoolgirls were abducted in Chibok, Nigeria by Boko Haram militants. Federal minister Oby Ezekwesili led the declaration of the #BringBackOurGirls hashtag.

2015 – Paris attacks

As the horrific attacks in Paris unfolded in November, the world united to support people in the City of Light using the hashtag #PrayForParis. Just 10 months prior, terrorists attacked the Paris offices of satirical magazine Charlie Hebdo. After that incident, citizens rallied around the phrase "Je Suis Charlie" to show their support and sorrow for the victims.

2016 – Leo finally wins

#Oscars: Leonardo DiCaprio's win for Best Actor in The Revenant generated 440,000 tweets per minute, more than @TheEllenShow's selfie two years earlier.