Taxonomies and Tags: From Trees to Piles of Leaves "But traditional taxonomic trees aren’t something we can throw away without a thought. They are an amazingly efficient way of organizing complexity because they enable us to focus on one aspect (e.g., that’s an apple) while keeping a universe of context (it’s a fruit, part of a plant, a type of living thing) in the background, ready for access. Tree structures are built into our institutions. They may even be built into our genes. So we are in a confusing and fertile period as we try to sort out what works and what doesn’t. Without trees, how would we organize college curricula, business org charts, the local library, and the order of species? How will we organize knowledge itself?"
"Faceted classification still presents users with a hierarchical tree, making it easy for them to browse to what they want. But unlike traditional trees, faceted systems don’t decide beforehand how the branches are arranged. For example, if an ice cream stand organized its “customer experience” around a traditional hierarchical taxonomy – a tree – it might have a customer first choose between two flavors, then among three sizes, and finally between a cup or cone."
"Tagging systems are possible only if people are motivated to do more of the work themselves, for individual and/or social reasons. They are necessarily sloppy systems, so if it’s crucial to find each and every object that has to do with, say, apples, tagging won’t work. But for an inexpensive, easy way of using the wisdom of the crowd to make resources visible and sortable, there’s nothing like tags."