title: Tag hierarchies and handling of
body: <p>This is a real issue that applies on tagging items in general (and yes, this applies to StackOverflow too, and no, it is not a question about StackOverflow).</p>
  
  <p>The whole tagging issue helps cluster similar items, whatever items they may be (jokes, blog posts, so questions etc). However, there (usually but not strictly) is a hierarchy of tags, meaning that some tags <em>imply</em> other tags too. To use a familiar example, the "c#" so tag implies also ".net"; another example, in a jokes database, a "blondes" tag implies the "derisive" tag, similarly to "irish" or "belge" or "canadian" etc depending on the joke's country origin.</p>
  
  <p>How have you handled this, if you have, in your projects? I will supply an answer describing two different methods I have used in two separate cases (actually, the same mechanism but implemented in two different environments), but I am also interested not only on similar mechanisms, but also on your opinion on the hierarchy issue.</p>