The Library of Congress Classification (LCC) sorts knowledge using letters — A for general works, B philosophy, Q science, and so on — which gives big research libraries far more room to expand than Dewey’s ten numbered classes. It’s the system most universities use.

When a collection runs to millions of volumes, ten Dewey classes start to feel cramped. The Library of Congress built its own scheme to shelve the largest library on earth — and because it scales so well, academic libraries the world over adopted it.

Letters first, then numbers

  • 21 broad classes, each a letter — e.g. Q science, R medicine, T technology, P language & literature.
  • A second letter narrows it — QA mathematics, QH natural history, QC physics.
  • Numbers and a cutter finish the address, pinpointing one exact book.
Dewey vs LC, same book
A physics text is 530-something in Dewey but QC in LC. Neither is “right” — they’re different maps of the same territory. The letter-based LC simply has more elbow room: 21 lettered classes (and room for more) versus Dewey’s fixed ten, which is why sprawling research collections lean on it.

Choosing between them

Public and school libraries usually prefer Dewey’s friendly numbers; universities and national libraries usually prefer LC’s capacity. Many a librarian works fluently in both — the skill is knowing why each suits its setting.

Try this
Find the call number on a book from an academic library. Does it start with a letter (LC) or a number (Dewey)? That first character tells you which map the library chose — and hints at how big it is.

🔗 A friendly free guide: Library of Congress Classification Outline

Whichever scheme shelves the book, the catalogue record behind it needs a format computers can share. That format has a name. On to MARC Records.

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Última modificación: viernes, 5 de junio de 2026, 08:07