Twitter is a social networking website on which people create profiles, “follow” or “unfollow” others, and communicate in posts of 140 characters or less, referred to as tweets. Besides communicating with friends through universal posts, @ posts that are directed to a specific persons, and private posts — called direct posts, Twitter users also have used Twitter posts to follow comments on particular topics and to have multi-person, international conversations. Because the posts are so brief and because there are so many tweets, the use of the hashtag, a name for the symbol #, was evolved by the Twitter community. The hashtag is used in several different ways.
The use of hashtags reported developed in 2007, when a user named Nate Ritter identified his updates about the forest fires in San Diego with a hashtag at the beginning of his posts:
#sandiegofire
As in this example, it is standard to have no spaces in a hashtag, and run multiple words together. More than one hashtag can be used, but they are separated by a space. Although Ritter put hashtags at the beginning of his posts, it is now a semi-convention to place any hashtags at the end of a tweet.
A variety of facilities, both on the Twitter site and in applications created to enhance the posting and viewing experience, allow for searches, and users can search for hashtags. This has led to the development of some hashtag uses. For example, the hashtag is an efficient way to categorize a post that may not have the category word in it. For example, a post about a new device or gadget might be marked:
#technology
This would allow people who are generally interested in technology, but not yet aware of the new device by name, to find the post.
Hashtags are also used to set off posts that are made by people participating in a conversation. Some conversations take place at a particular time each week, and some are ongoing. The hashtag:
#musedchat or #MusEdChat
is used by music educators who meet to chat on Mondays, but also post in between.
Hashtags.org™ is a website that evolved to follow Twitter trends and encourage recognition of them by promoting the use of hashtags to categorize posts. At one time, it also allowed users to sign up with a profile and apply three hashtags to their Twitter ID names, in order to help like-minded people find each other. In 2010 it was essentially offline for a number of months and undergoing reorganization, but planning a comeback with new features.