The Hashtag (#)
February 9, 2012
The # symbol, or 'hashtag' is used in Twitter. A hashtag shows that a tweet relates to a certain category or event. When a hashtag is used by a large number of users, it can become a trending topic. The hashtag has many creative uses; it is most commonly used for events, topics, and public chats. For example, a group of people can use a hashtag in their posts to have a chat that anyone on Twitter can observe and join. If you search for #MMchat ('Marketer Monday chat') on Twitter, you will find relevant posts about marketing (for example, @SocialCMO hosts chats on Twitter using #MMchat).
When you post on Twitter, you can make your post more findable by including a hashtag. Do not use a hashtag that will be used by your organization and no one else. A hashtag is what brings tweets together from several different tweeters. Also, don't overuse hashtags (i.e. "I just ate a #sandwich that was so #delicious. #yum #wow #turkey). The hashtag #elearning is used by Twitter users talking about the topic of e-learning. Using a hashtag is appropriate because it is a shared topic centered around a specific issue. Here is an example tweet by Miguel Arias:
When searching for relevant posts on a topic, the hashtag is helpful. If you want to read tweets about MIT, and you type 'MIT' into the Twitter search box, your results might include official MIT tweeters, but would also include any posts containing the letters 'MIT' - such as posts about Mitt Romney and posts in German (mit is the German word for with). However, try searching for #MIT using the hashtag. You will get posts talking specifically about MIT. The hashtag is also interactive. When a word is preceded by a hashtag, it becomes a live link that when clicked will bring up all recent posts on Twitter that use that hashtag. If I want to hear more posts on this topic, I can click on the hashtag and read all tweets that use that hashtag. This is one way to search for many posts on one topic. When you click on "#elearning" in Miguel Arias' post, you are led to all twitter posts that use the hashtag #elearning.
The basics of hashtags in the Twitter help center
The Twitter Fan Wiki: an introduction to hashtags and how to use them
'Hash' by Susan Orlean in The New Yorker (June 2010)