What was the first widely recognized hashtag used on Twitter?

The first widely recognized hashtag used on Twitter was #barcamp.

The tag appeared in 2007 in connection with BarCamp, a network of user-generated conferences and unconferences. Hashtags gave people a simple way to attach a searchable label to posts and follow a shared topic across otherwise separate conversations.

Chris Messina proposed using the number sign for group discussions on Twitter in August 2007. Twitter did not immediately create an official hashtag feature, but users adopted the convention organically, and it eventually became a central part of the platform’s conversation structure.

The first hashtag is sometimes incorrectly identified as #Twitter or linked to later major events such as the Arab Spring or the 2009 Iranian protests. Those events helped popularize hashtags, but they came after #barcamp’s early use.