In a August 23, 2007 tweet[5] Chris Messina first proposed vertical/associational grouping of messages, trends, and events on Twitter by the means of hashtags. Messina intended the hashtag
"as a type of metadata tag that allowed users to apply dynamic, user-generated tagging which made it possible for others to easily find messages with a specific theme or content; it allowed easy, informal markup of folk taxonomy without need of any formal taxonomy or markup language. Hashtags have since been referred to as the "eavesdroppers", "wormholes", "time-machines", and "veins" of the internet.[6]
On Twitter Messina asked, "How do you feel about using # (pound) for groups. As in #barcamp [msg]?"
