Hashtags

Hashtags Introduction 

Hashtags are a community-driven convention for adding additional context and metadata to your tweets. They're like tags on Flickr, only added inline to your post. You create a hashtag simply by prefixing a word with a hash symbol: #hashtag.

Hashtags were developed as a means to create "groupings" on Twitter, without having to change the basic service. The hash symbol is a convention borrowed primarily from IRC channels, and later from Jaiku's channels. 

hashtags.org provides real-time tracking of Twitter hashtags. Opt-in by following @hashtags to have your hashtags tracked.  Similarly, Twemes offers real-time tracking without the necessity of following a specific Twitter account.  Also, with their purchase of Summize, Twitter itself now offers some support of hashtags at their search engine: http://search.twitter.com. Other services such as TweetChat, TweetGrid, and Twitterfall are also popular for following hashtags in real-time.

How To Use Hashtags

Start using hashtags in your tweets, preceding key words. It can be helpful to do a little research first, to find out if the subject you're tweeting already has an established hashtag. Also, check Suggestions and Tips and Example Uses below for ettiquette and general usage.

Finally, track other tweets on the subjects you're interested in (ie: those containing the appropriate hashtags) by browsing/searching at Hashtags.org, TwitterGroups,TweetChat, TweetGrid, Twitterfall, etc. You can set it up with RSS feeds as well.

Use of hashtags 

Hashtags were popularized during the San Diego forest fires in 2007 when Nate Ritter used the hashtag "#sandiegofire" to identify his updates related to the disaster.