Whenever a new Web trend comes along, there are people who ask, "What is the point of this?" If millions of people are using something, there has to be a reason. In our What Is the Point of... series, we'll explain it to you.

This week, we're asking, What is the point of #hashtags?

What Is a Hashtag?

The hashtag was invented as a label for groups and topics in IRC chat. By adding the '#' sign before a string of text, users made that string easy to find in a search. But the hashtag went mainstream thanks to Twitter.

In 2007, as Twitter was just picking up steam, Chris Messina - an open-source software champion currently at Google - tweeted what is believed to be the original proposal that Twitter users adopt hashtags as well.

Related: The First Hashtag Ever Tweeted on Twitter - They Sure Have Come a Long Way

It caught on. For a long time, it was just a hack; hashtags were simply plain text in a tweet that could show up easily in search. Twitter's early-adopter crowd used hashtags like "#barcamp" (for BarCamp open-source conferences) or "#sxsw" (for South by Southwest) to filter their messages. Nate Ritter's #sandiegofire hashtag became one of the first news topics to go viral during the October 2007 California wildfires.

Twitter Makes It Official

By July 2009, Twitter had realized what an ingenious trick its users had invented, so it began to turn hashtags into links. When a Twitter user clicks on a hashtag, it goes to the stream of tweets containing that hashtag. You can also find hashtags using search. This is how you find things on Twitter by topic.

Related: How To #FollowFriday

In 2010, Twitter introduced Trending Topics, so Twitter users could see what the world was talking about right this minute. Hashtags that became popular quickly would shoot to the top.

Then something terrible happened.

Trending topics became completely full of stupid. As Twitter's user base climbed into the hundreds of millions, the kinds of hashtags that won out were quite unlike the newsworthy or conference-centered ones that early adopters used. A trending hashtag in the past year or two was more likely to be something like "#ThingsISed2UrMamaLastNight" or "#ReplaceMovieTitlesWithPoop."

But it's getting better. As Twitter turns its new Discover section into its business, it has begun to do much more diligent filtering of trending topics, as well as better localization of the topics it shows to you. So hashtags are becoming useful for finding out what's going on.

How To Use Hashtags

Joke hashtags can be fun when they're popular, but remember that a hashtag is a search. They're meant to label a topic or filter a conversation. In some Twitter apps, you can mute a hashtag to avoid seeing chatter you don't want to see. So for instance, if you hate when people live-tweet sports games, you could mute #sports, so you wouldn't have to see tweets containing that tag.

The problem is, everyone would have to include #sports in their sports tweets for that to work. If you're tweeting a lot about a topic, you should probably include a good, general hashtag. That way, your followers can mute it if they don't care, or they can explore it if they do.

(And if I may include a personal plea: PLEASE tag your sports tweets with #sports.)

Lead image via Shutterstock.