Happy birthday, #!
Back in 2007, Twitter user @chrismessina thought the hashtag would be a good way to make groups.
He originally tweeted #barcamp - an international network of user-generated conferences primarily focused around technology and the web - so it could be an easily searchable terms for groups, themes or topics.
And now the hashtag gets used on average more than 125 million times per day.
Hashtag use has grown considerably. In 2007, the most tweeted hashtag was used about 9,000 times. This year, the most popular hashtag has been used over 300 million times.
Memorable moments like #batkid captured the country's attention when a cancer-stricken boy got his "Make-A-Wish" granted to play a superhero across San Francisco or #IceBucketChallenge which involved people pouring cold water over themselves and posting the video on social media. It's also been used to spark conversation around social issues such as the campaign to draw attention to nearly 300 kidnapped Nigerian children with #BringBackOurGirls or police misconduct with #BlackLivesMatter.
In celebration of its birthday, Twitter created a 24-hour custom emoji. To check it out, just tweet #Hashtag10.