In what year was the first hashtag tweet posted?

The first hashtag tweet was posted in 2007. Chris Messina used Twitter that year to propose placing the hash symbol before words or phrases so users could group and follow related messages.

Messina’s proposal was influenced by Internet Relay Chat, where the # symbol had long identified channels and topics. Twitter was still a relatively young service, and its short public messages lacked a built-in system for organizing conversations. A searchable label such as #barcamp could provide a simple, user-created way to connect posts without requiring a central editor or formal classification system.

The idea was not immediately embraced by Twitter. Its usefulness became clearer during the 2007 San Diego County wildfires, when people used the hashtag #sandiegofire to follow developing information. This helped demonstrate that hashtags could organize fast-moving public conversations, not merely personal posts.

Hashtags later became standard across many networks. Although the first proposal and early adoption happened on Twitter, the concept now supports topic discovery, live-event discussion, campaigns, activism, marketing, and community conversations on numerous platforms.