Something about hashtags in Twittertwitter is simply a keyword or abbreviation, preceeded by a hash (or pound sign: #), for instance #icantinternet could be used for all tweets about this blog. Or #bushfire can be used to group all tweets about the Australian bushfires. Something that could never be done without the hashtags.
So how can you find all those tweets then?
Easy, take a look at http://search.twitter.com, and search for the hashtag of your choice. Thanks to the enormous popularity of Twitter, there are also numerous apps out there on the internet that help you with the use of hashtags, such as http://hashtags.org
You can follow me on twitter via http://twitter.com/icantinternet
And this time, if you see Hashtags in Twitter in your timeline you know what they are 😉