Once you’ve started using Twitter, it won’t take long before you come across what’s known as a hashtag. That’s when you see something in a tweet that has a # prefix. (The # is a hash symbol, hence the term hash tag or, more commonly now, hashtag.)

For example, if you’ve seen tweets related to the recent typhoon that has devastated the Philippines, you may have noticed some of them had #Haiyan in them.

A hashtag is simply a way for people to search for tweets that have a common topic. For example, if you type #Gravity into the Search Twitter box at the top of any Twitter page and hit Enter, you’ll get a list of tweets related to the movie. What you won’t get are tweets that say “Who discovered gravity?” because “gravity” isn’t preceded by the hashtag.

The good thing about the hashtag is that if someone wrote a tweet without putting the word Gravity in the main message, it will still show up in your search because of the tag. Eg. “Just saw this year’s best picture. #Gravity”

The flip side is that if you search using the tag, and someone wrote a tweet about the movie without including it, that tweet may not show up in your results, even if Gravity appears in the text. Eg. “Who thinks Gravity will win Best Picture this year?” (Sometimes it does, but not always.)

In a way, hashtags allow you to create communities of people interested in the same topic by making it easier for them to find and share info related to it.

Where do hashtags come from?

This question gets to the heart of the confusion about these danged things, because hashtags are NOT any kind of official Twitter function. The company has not created a list of topics that we can browse through to see if there’s one that interests us.

So where DO they come from? Well, any user can create one simply by adding it to their own tweet. For example, when a plane went down in the Hudson River a few years ago ago, some Twitter user wrote a post and added #flight1549 to it. For something like this, where tweets would have been flying fast and furiously, it wouldn’t have taken long for this hashtag to go viral and suddenly thousands of people posting about it would have added it to their tweets as well. Then, if you wanted info on the situation, you could do a search on #flight1549 and see everything that people had written about it.

When hashtags first started being used, it was a very organic process that worked simply because of a group mindset that people like to categorize topics and this was one way to make it easier to do so.

Now that they are so common, they really only show up spontaneously if there’s a breaking news item. Otherwise, they’re used to promote, praise, or pan people (#Malala), brands (#Lego), events (#StanleyCup), and anything else people want to discuss en masse (#bacon).

There are a few other common ways hashtags are used as well:

  • Group Activities. These are things like college classes, conferences, clubs, associations, or online events, where there’s a certain group of people who want to share information among themselves through tweets (although be aware they’re still available to the general public).
  • Online Conventions. These are usually short terms or abbreviations that have become common ways to express certain concepts. Some examples are#shoutout, #nowplaying, #tbt (Throwback Thursday).
  • Asides. These are little extras people add to their tweets to express the way they feel or make a comment about what they just tweeted, e.g. #blessed,#mustread, #smh (shaking my head).

How do I track topics of interest to me?

The first thing you would do is a basic Twitter search to see if a related term already exists. These days, odds are it does.

Probably the only reason you would need to create a new one nowadays would be for the group activities category. In that case, since the tag will use up some of your 140-character limit, you want to keep it fairly short, while still making it precise so other people aren’t likely to use it for another purpose.

If you want more than just your friends to use the hashtag, you might want to “announce” it to your followers.

Why doesn’t my hashtag show up in searches?

There are two possible issues here. One has to do with whether there’s an issue with the hashtag itself. Twitter’s Help page explains some of the problems you can run into—for example if a hashtag is made up entirely of numbers, Twitter doesn’t make it searchable. However, in most cases, this is NOT the problem.

Instead, the problem is actually with Twitter’s own search feature.