The Importance Of Keeping #politas On Topic

This is a piece concerning Twitter I've been meaning to write for some time, mainly so I can link to it and so others can link to it when explaining the concept of topicality to people determined to ignore it or else new to Twitter.  Or who just don't know what "#politas" means.

On Twitter, hashtags are used to to help people find material that is relevant to them.  If a person is interested in something, they can use TweetDeck or other programs to set up a search for all tweets with a particular hashtag (a # followed by the subject matter), and thereby "follow" that hashtag.