Index cards stacked

Stacked index cards, a traditional manual information organization system used in libraries and archives before the digital age.

About this subject

Index cards, also known as catalog cards, were widely used in libraries, archives, and offices to organize information manually. Each card, typically in the standard 3x5 inch size, contained data such as title, author, subject, and location of books or documents. The system was popularized by Melvil Dewey, an American librarian who also created the Dewey Decimal Classification. Cards were stored in drawers or boxes, enabling quick retrieval by alphabetical or numerical order.

The use of index cards dates back to the 19th century, but peaked between the 1950s and 1970s, when libraries worldwide maintained massive card catalogs. Color coding, tab positions, and divider guides aided visual categorization. In Brazil, institutions like the National Library adopted this system, which required specialized training to maintain consistency.

With computerization, card catalogs were gradually replaced by digital databases. Yet index cards persist in specific contexts, such as field research, creative project notes, or systems like Zettelkasten, a note-taking method used by writers and scholars. Their simple design and portability keep them relevant even in the digital age.

Frequently Asked Questions

What is the origin of index cards?

Index cards originated in the 19th century as library collections grew. American librarian Melvil Dewey was key in standardizing the format and cataloging system around 1876.

What is the standard size of an index card?

The most common size is 3x5 inches (7.5 x 12.5 cm), but variations like 5x8 inches (12.7 x 20.3 cm) and 4x6 inches (10.2 x 15.2 cm) exist depending on the need.

Are index cards still used today?

Yes, though less frequently. They are used in creative methods like Zettelkasten, manual academic research, and environments where digital systems are impractical, such as remote fieldwork or historical archives.