The Librarian's Dilemma: On the Classification of Ambiguous Things
I’ve been reading about the history of library science lately, and it’s striking how the fundamental challenge of a major search engine echoes that of a great library. Both are tasked with taking a universe of unorganized information and imposing a system that allows for discovery. But what happens when the items in that collection defy easy categorization? This is the librarian’s dilemma, and it’s a problem that haunts the edges of every crawler’s index.
Consider a book that is part memoir, part philosophical treatise, and part cookbook. Where does it go on the shelf? The Dewey Decimal System demands a single, primary location. An eager junior librarian might zealously pick the most prominent theme and shelve it there. But in doing so, they relegate the book’s other identities to secondary status, making them discoverable only to the most persistent patron. A seasoned librarian, however, understands the power of the cross-reference. They create multiple entries in the card catalog, ensuring the book can be found from several angles of inquiry. The book itself lives in one place, but its presence is felt in many.
Our web crawlers face the same judgment call with pages that serve multiple, often conflicting, purposes. A single product page might also contain a lengthy tutorial, user testimonials, and a technical whitepaper. A crawler, like the junior librarian, is often forced by the structure of a site and the explicit signals of its markup to choose a primary classification. Is this a ‘product’ page or an ‘article’? The answer isn’t always clear, and the wrong emphasis can make the page’s valuable secondary content virtually invisible to specific search queries.
This is where we, as the architects of a site’s structure, can learn from the old masters of the library. We can build a rich system of internal cross-references. We can construct topic clusters that link tangential but relevant content, acting as a guided tour through a subject’s many facets. We can use structured data not as a single, loud label, but as a quiet, nuanced set of descriptors that tell the crawler, "This is also about that." The goal isn’t to force a page into a single box, but to acknowledge its complexity and create multiple paths to its doorstep.
The most enlightened librarians knew that a perfect, rigid classification system was a myth. Humanity’s knowledge is messy and interwoven. The true art lies not in forcing neatness upon the chaos, but in building a flexible network of connections that respects the ambiguity of the material. For our digital domains, the lesson is clear: our sites should not be static shelves of isolated pages, but dynamic, interconnected collections where the richness of a page’s content is highlighted by the many ways it can be found. We must build not for the crawler that needs a single answer, but for the librarian-crawler that appreciates a good cross-reference.
Notes & further reading
A few pages I came back to while writing this: