Hashtags work like keywords, but they’re more deliberate. A hashtag is simply the use of the pound or number (#) symbol in a Twitter post. Using a hashtag indicates that you intend to start or join a conversation about a specific topic. For example you may see hashtags used at conferences or on TV shows. This is a way for conference organizers and TV producers to be certain their fans and followers are following the same conversation, rather than having various unconnected conversations. Without a hashtag some people might search for keywords that actually relate to another topic and they might miss out on the conversation because it isn’t “organized” under a specific hashtag.
You can follow keywords on Twitter with or without hashtags, but hashtags give us a nice way to organize conversations and even develop communities.
If you Tweet with a hashtag on a public account, anyone who does a search for that hashtag may find your Tweet, not just your followers. And likewise you can find tweets from other users, not just those you follow.
Remember to not #spam #with #hashtags and don’t over-tag a single Tweet. (Best practices recommend using no more than 2 hashtags per Tweet.) Use hashtags only on Tweets relevant to the topic.
Try this example:
Use the #Discover tab on Twitter to search for the keywords “IAHawks” and also “Hawkeyes“. You’ll see the “Hawkeyes” stream is definitely “the”#Hawkeye hashtag to follow. Try some other keywords you’re interested in. Try searching on them with or without the hashtag and see the difference in the results. The hashtags filter the responses so you can see the comments that intend to be a part of the conversation and not just casual mention of the word.
In TweetDeck you can set up different columns to follow different keywords and/or hashtags. It works pretty slick. I use them to seek out conversation about conferences I’m interested in and comments about my customers.
Twitter provides a nice explanation of the hashtag here. https://support.twitter.com/articles/49309-what-are-hashtags-symbols.
And the page for Twitter developers also provides some tips. https://dev.twitter.com/media/hashtags.