Twitter is celebrating 10 years of the hashtag today (August 23) and many are looking back on the key which revolutionised social media.
The hashtag was created by former Google and Uber engineer Chris Messina, who simply tweeted the idea out as a suggestion way back in 2007, according to BT.
It seemed most people liked the suggestion. By the end of the year the popularity of using the hashtag had grown significantly.
Now on average 125 million hashtags are posted to Twitter each day and according to the Financial Express the most popular one is #FollowFriday, used to encourage users to follow other accounts.
But The Metro reports that the most used Twitter hashtag so far this year is #BTSBBMMAS, which celebrated K-Pop band BTS winning at the Billboard Music Awards.
This is very different to the top hashtag back in 2007, as the most used one was #noticias, the Spanish word for news.
Hashtags have also been used for more serious campaigns and two of the most prominent have been #BlackLivesMatter and #IceBucketChallenge.
But hashtags aren't just simply text any more, Twitter now adds emojis to some hashtags, much like today as #Hashtag10 features an emoji of - you guessed it - a hashtag, although this one has the added extra of a balloon.
Twitter has also revealed more facts about hashtags and says the most used TV hashtag on the site is #TheWalkingDead but the most used film hashtag is #StarWars.
They've also covered sport as well and revealed the most tweeted hashtag for a team is #MUFC, which of course stands for Manchester United Football Club.
Take a look at the reaction on Twitter to the anniversary below