Written by: Don Worthley
5/2/2008 8:42 AM

Should they be separate or the same?  It used to be that this question related only to blogs, but now you'll find both of these metaphors used in online stores, in forums, in comments related to products or related to news articles.  An interesting approach was suggested for blending the two ideas into one last week by one of the members of the DotNetNuke² community.

OK, here's how it it all started.  The blog team is currently in the process of thinking through some of the needed enhancements to the module and Rip Rowan, a fellow DotNetNuke blog team member, got me thinking yesterday about some really interesting ideas related to assigning categories to the DotNetNuke blog module. 

Well, when I read Rip's post, I sent him an email saying, "Call me if you have the time to chat!"  A few minutes later the phone rang and Rip warned me, "OK, you've gone and done it now!"  Indeed.  It was a fascinating conversation that I would like to capture quickly in the blogosphere to bring other people's thoughts into the mix. 

Rip is proposing a new idea (new to me at least) for categorizing blog entries.  Basically, he's come up with an idea for an interface that would combine the concept of a category with the concept of tagging or keywords to produce one control and one underlying data structure in the database to manage the process of putting a handle on your blog entries.  Rip describes it like this:

...My idea is the use of a hierarchy delimiter.  The user can create hierarchies as deep as they like, and the auto-suggestion box helps them out.  So a blog post might be tagged up as follows:

--------------------
[MyBlogPost]
Tags: [Places\Dallas; Places\New York; Places\Paris; Foods\Steak; Foods\Fish; Foods\Pizza; Time of Day\Morning; Time of Day\Evening]
--------------------

The data-entry UI would automagically suggest each portion of the hierarchy at a time, so when the user types "Pl" the textbox responds "Places", and the user hits the delimiter key "\" to accept and begin entering the next hierarchy component:

--------------------
Tags: (type) Pl
Tags: (UI responds) Places
Tags: (type) Places\ (user enters delimiter key)
Tags: (UI presents) Places\[drop-down list of places in the places list, if list is < 10 entries]
Tags: (type) Places\Dal
Tags: (UI presents) Places\[drop-down list: Dalhart Dallas Dalton]
Tags: (user selects Dalhart)
Tags: (UI presents) Places\Dalhart; (adds delimiter so user can begin entering next tag)
--------------------

Here was my response to Rip on the phone.  The fact that the publishing industry has used two distinct metaphors for assigning meaning or placing handles on the content for years makes me think there may be something to the distinction between categories and tags that should be maintained.  Here's how Rip makes his point in a second post on this same subject.

I'm inclined to view "tags" and "categories" as just two facets of the same thing: knowledge hooks we apply to content to help us find it.  My gut tells me that these things tend to be viewed as two different beasts because of the way they've historically been implemented.

Rip goes on to make the point that tags are really just ad hoc attempts at capturing semantic meaning that should already be captured in some kind of categorical data structure.

Speaking of the kind of tags that get created, Rip says,

If you look at what sort of tags get created, it becomes plain that there are three sorts of tags:

1. Spurious tags - tags that duplicate existing attributes and shouldn't be there in the first place, e.g. "Monty Python" tag associated with the movie "Monty Python and the Holy Grail" which has an artist of "Monty Python", or tags which just don't add practical value, like "Movies that Include the word 'swallow'".
2. Tags that ought to be part of a data structure that just doesn't exist - e.g. "Graham Chapman" tag on "Holy Grail", which really ought to be part of a structure called "Actors" but isn't provided by Amazon.  Or "British Comedy" which really should have been a subset of the "Comedy" genre, but Amazon didn't provide this option.  Or "Arthurian Legends" - a tag that could easily have been a category in the "Subject Matter" hierarchy.  Or "Party" - a tag that could well belong in a "Mood" category.
3. Tags that don't seem like they should be part of a data structure, YET, because not enough material has been tagged on this dimension to understand the dimension.  For example, your hypothetical post that you wanted to tag "suggestions", could easily have been a node in the "Article Type" category, along with "Ratings", "Reviews", "Comparisons", and "Recipes"

On one level, I agree with this.  Tags and categories are both attempts at overlaying semantic meaning onto the published content to aid in discovery and retrieval.  But, on another level, it seems we should be careful about dismissing the separation that has existed for years in the publishing world between the table of contents and the index.  We may lose something by combining these two.  The one provides a nice thirty thousand foot view of our content using broad, rigid structures that are created to capture carefully labeled buckets for the content we have or intend to publish.  The other (tagging) allows content providers to reach into the semantic world a little deeper and provide synonyms and words or phrases that may slice across a variety of the predefined categories.

In a third post, Rip links to another blog entry which highlights how keywords³ and categories are implemented in WordPress 2.3.  This really gets to the heart of the issue.  Should keywords/tags and categories be managed through the same table at the data layer?  I think this may be a good approach since it allows for the best of both worlds.  Two distinct user interface components could be created to allow for both the hierarchical, more structured semantic meaning achieved through categories as well as the ad hoc, more finely grained meaning captured by tags.

Thoughts Regarding Implementing a Categorization Interface in the Blog Module

I like the interface that Rip has suggested.  I can see that for people with tall lists of categories, finding the right category may be time consuming, especially if a node in the tree contains a large number of entries.  Of course, if I had to guess I would say that most people using the blog module for publishing will have relatively simple category hierarchies.  In this case, requiring that users select categories using a textbox with AJAX would actually be more time consuming.  Another possible metaphor for category selection, would be a treeview with checkboxes for easily assigning multiple categories.  For smaller taxonomies, this would allow the user to assign categories with a few clicks.

What do you think?  That's what I'm really interested in knowing!  Even if you're not using a blog module, customers of any site today expect to see standard forms of categorization.  Should categories be separate from tags, or could a new interface be used which combines them both?  Or, maybe you have a blog entry of your own that's been brewing in your mind!  Join the conversation and let us know what you think! 

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