Christopher Reaves Messina (born January 7, 1981) is an American blogger, product consultant and speaker who is the inventor of the hashtag as it is currently used on social media platforms.

[1][2][3] In a 2007 tweet, Messina proposed vertical/associational grouping of messages, trends, and events on Twitter by the means of hashtags.

As in #barcamp [msg]?Although Twitter's initial response to Messina's proposed use of hashtags was negative, stating that "these things are for nerds"[5] a series of events, including the devastating fire in San Diego County later that year, saw the first widespread use of #sandiegofire to allow users to easily track updates about the fire.

The use of hashtags itself then eventually spread on Twitter, and by the end of the decade could be seen in most social media platforms including Instagram, Facebook, Reddit, and YouTube.

[18] In 2008, he won a Google-O'Reilly Open Source Award for Best Community Amplifier for BarCamp, Microformats and Spread Firefox.

[19] In February 2018, Messina launched Molly, an AMA-style website where the questions are answered using the person's social media posts.

The value and satisfaction I derive from seeing my funny little hack used as widely as it is today is valuable enough for me to be relieved that I had the foresight not to try to lock down this stupidly simple but effective idea."

Channels or topics that are available across an entire IRC network are prefixed with a hash symbol (as opposed to those local to a server, which use an ampersand).

[22] The use of the pound sign in IRC inspired Chris Messina to propose a similar system to be used on Twitter to tag topics of interest on the microblogging network.

According to Messina, he suggested use of the hashtag to make it easy for "lay" users to search for content and find specific relevant updates; they were for people who do not have the technological knowledge to navigate the site.