What are tags?
Tags are free-form metadata that can be added to all entry types. Tags allow users to link entries together by any properties they can come up with, not being limited to the options provided by the system. Examples of tags are genres, presentation languages and themes. Tags can be edited more freely than other properties and some of them they may even be considered subjective. Therefore tags are based on voting. Any user may add tags to an entry and vote on existing tags. Only the most popular tags will be displayed for that entry.
What to tag then?
Generally you should avoid tagging with information that is already provided by more specialized fields. For example, albums or songs with artist names is redundant because the artists list already handles this better. Likewise, tagging cover songs with "cover" is useless if the song classification is already cover. Of course albums have no such classification, so that tag might be relevant for an album (for example, tagging an album entirely made up of covers).
Most tags should be objective, meaning their validity isn't based on the listener's subjective opinion. For example, "beautiful" is a poor tag because beauty is highly subjective. "Calm" is a slightly better tag, since that can be defined by some objective characteristics, although it's still mostly subjective. Please prefer creating private song lists for highly subjective properties.
Tags versus pools
Trusted users are able to create public songlists called pools. Pools can be used for largely the same purpose as tags, grouping songs together based on some common theme (such as album "tours" on NND). There are a few differences between tags and songlists:
- Pools are not voted on, unlike tags. All pools are equal.
- Only trusted users are able to edit pools. Any user can vote on tags. Thus tags are easier to use, but also more unreliable.
- Pools may contain only songs. Tags can be applied to albums and artists as well.
- Songs in a pool can be ordered. Songs with a specified tag are unordered.
- You can add notes to songs in a pool.