Should tagging have heirarchies ??

Question

i have always viewed tags as completely different than the normal folder hierarchy model. I am building a system that needs tagging to tag sets of data. We had the db design all worked out, (pretty straight forward model) but a debate arose around the value of still having concepts of hierarchies within a world of tags.

On SOF, as an example, the only equivalent i see some of this by using "-" in some tag names like tagging; "jquery", "jquery-ui", "jquery-ui-dialog" so there is no inherent modeled relationship (just naming convention)

is there any conventional wisdom of best practices around how and if hierarchies should exist in a world of tagging.

Answer 1

I developed a portal that involved hierarchical tags. I can assure you that is a mess to manage :)

My solution then moved to a hybrid approach in which tags can be stand-alone or hiearchically handled but they reside in two different namespaces.

This because some tags can be seen as children of parents of other tags while others cannot, so for example dialog tag is a concept that is also indipendent from jquery so a content with both tags jquery dialog has implicitly the relationship needed.

Hierarchical should be used to express a kind of inheritance between concepts, eg. collections -> trees, lists, maps in which trees tag can be effectively included inside a collections tag.

In your example dialog and jquery are orthogonal and uncomparable, so it makes no sense to make one child of another.

Answer 2

The names "jquery", "jquery-ui", "jquery-ui-dialog" aren't tags, but the equivalent of file structure paths, hierarchical by nature.

If your data is easy to authoritatively categorize then present it as a tree. If users only see a few of their own tags (like in Gmail), you could make it possible to sort and nest the tag list and save that structure per user, separately from tags themselves. If there are great many tags with power distribution of content (for example if 10% of tags describe 90% of content) then a tag cloud can help.

In short, it depends on the data.