Of Taxonomies and Crumbtrails

By Deane Barker on August 15, 2004

I’ve had an eternal struggle with taxonomies and crumbtrails and I’ll share it with you now in the hopes of finding some resolution that will let me sleep. (Okay, it’s not THAT bad, but I have been tossing this around for days now with no solution.)

A taxonomy is a parent-child classification system. Most every site has one whether it was planned or not. I work for a commercial real estate firm, and we have a simple taxonomy, some of which looks like this:

Home Property Office Industrial Land Retail Investment

For the most part, this works fine. It’s simple, and it makes sense.

Taxonomies also lend themselves nicely to crumbtrail navigation. If I’m looking at a property in the Office category, I can get a crumbtrail like this:

Home > Property > Office

However, there are situations that require a piece of property to fit into more than one category. For instance, there are many buildings that can legitimately be used for both office and retail. Therefore, the property needs to appear under both categories because people browsing either would be interested in it. This is no problem, as taxonomies are supposed to be able to handle this.

But what about the crumbtrail? If I’m looking at a property that appears in both Office and Retail, which crumbtrail do I get:

Home > Property > Office Home > Property > Retail

I can think of two things:

Primary and Secondary Classification Pick one “true” classification for the property. Just make an arbitrary decision if its Office and Retail and classify it as such. Let it appear in the other category as well, but the crumbtrail should reflect its “true” classification.

A couple problems here:

(a) Maybe something legitimately fits equally in two places. Say one side of taxonomy classifies by property type (Office, Retail, etc.) and another by size (less than 5,000 sq. ft.; 5,000 – 20,000 sq. ft., more than 20,000 sq. ft.). No matter how hard to you try, any property is going to fit in more than one category.

(b) If someone browses to a category from a “secondary” trail, they’re going to be confused because the crumbtrail doesn’t reflect where they came from. Say I give a building a classification of Office but also let it appear as Retail. If someone browses to the property through the Retail trail, then tries to walk back up the trail, they’re going to be sent back to Office, instead of Retail where they came from.

Dynamic Crumbtrails You can always create the crumbtrail based on the trail the user actually came from. So if a user browses to our property through the Retail trail, display a trail based on that. If they came from Office, display that crumbtrail.

This seems good, but what if the user didn’t browse and was linked directly? Then what do you use?

So, there you have my quandary. If anyone has a resolution or a thought, let’s hear it.

Comments (5)

Adam Kalsey says:

Why not combine both approaches. Show a dynamically-created trail when you know where they came from and a default trail on direct links?

The other question is are the breadcrumbs really useful for your site? I’ve seen some research (can’t find it now, sorry) that indicates breadcrumbs are useless for many types of sites. You might want to study this either through some click tracking or by watching actual users.

chizh says:

things you might want to look at

facet maps are probably the closest to breadcrumbing. http://facetmap.com:8080/index.jsp

a good practical example of a facet-based website i particularly like is http://mathworld.wolfram.com/Tree.html

and of course topic maps http://www.topicmaps.org/xtm/


Simon Willison says:

This problem gets even tougher if your navigation is based on the crumbtrails. If a piece of content exists in two locations on a site, which location should you display in things like search results (assuming you don’t want to display the same content twice)? I wish I had an answer!

gabriel says:

If you have content that will present you this problem, then crumbs are not the tool to be used. how difficult is that?

use what works. This goes against your “the early 85%” post. If you did your homework you’d know crumbs aren’t to be used here. But you are hammering the crumbs, detecting where the person came from and adapting it, to make it solve your problems on the last 15%.

study your content and use what makes sense.