Tags have two purposes:

  1. To organize what needs to be done. For example, by searching for all topics tagged with missing-summary, we can easily locate topics which need a summary. Same for missing-example-problems, etc.
  2. To help me find puzzles. For example, has-cryptarithmetic-puzzles can be searched for to find all topics containing at least one cryptarithmetic puzzle.

Some things have a state:

Here are some examples:

Other tags are used purely for search:

You can use the following PHP code to list all topics containing cryptarithmetic puzzles:

list_topics_by_tag('Cryptarithmetic puzzles', 'cryptarithmetic-puzzles');