The Twitter hashtag (pound sign) is used in front of a keyword in a tweet. It helps people to search for tweets with that keyword in them. It can also help you to get the most out of using Twitter as a communication tool.
Twitter helps you to build a network to get and share information. In order to do both, you need to work to build your connections. Some of this will happen organically – twitter users will follow you once you start tweeting. Follow the people who follow you.
You can also find people to follow with Twitter directories like WeFollow. While you are there, be sure to list yourself.
Hashtags can help you find who is talking about a topic, whether or not you are connected to them.
Tools to help you find hashtags you may want to follow or to define one of your own:
Twitter is a great way to build excitement about an event. When you tweet about an event, other people can easily retweet giving your information even more exposure.
Create a hashtag for each special activity or event, so you and other people can Tweet about it. The hashtag can then be used to index all the tweets about your event.
Remember to have a friend, be a friend. So, if you see other people tweeting out their event give them a hand and they will do the same for you.