Dewey Decimal System Day Date in the current year: December 10, 2024

Melvile Dewey was an influential American educator and librarian. He is best known for inventing a system of library classification that is widely used in public and school libraries around the world. Dewey created his system fresh out of college while working at the library of his alma mater, Amherst College. He published the first version of the classification in 1876 and copyrighted it.

The Dewey Decimal Classification (DDC), often referred to as the Dewey Decimal System, is a library classification system which allows to add new books to a library on the basis of their subject and makes it possible to easily find any book on the shelves and return it to its proper location. More than 200,000 libraries in at least 135 countries around the globe use the Dewey Decimal System to organize books.

The system is called “decimal” because it comprises ten main classes that are supposed to cover the entire world of knowledge:

• Computer science, information and general works
• Philosophy and psychology
• Religion
• Social sciences
• Language
• Pure Science
• Technology
• Arts and recreation
• Literature
• History and geography

Each class is further divided into ten divisions, and each division has ten sections. Each number assigned to a book in the Dewey System consists of two parts: the class number and the book number, the latter preventing confusion of different books covering the same subject.

Of course, nothing is perfect, and Dewey’s system is not an exception to this rule. It has been criticized for being too complex and hard to amend, its treatment of homosexuality, religion and women, and for being proprietary, which makes it expensive to adopt. However, the DDC remains the most widely used library classification system in the world despite all its imperfections.

The origins of Dewey Decimal System Day are unclear, but the choice of its date makes sense, since December 10 is Melvil Dewey’s birth anniversary. This holiday may not be insanely popular, but it is celebrated by librarians and book lovers from around the world because the Dewey Decimal System makes their lives so much easier.

You can celebrate Dewey Decimal System Day by reading about Melvil Dewey and his greatest invention, visiting your local library and talking to librarians about the benefits of the Dewey system, taking the Dewey Decimal Challenge, in which you have to read at least one book from each of the system’s ten principal classes, and post on social media with the hashtag #DeweyDecimalSystemDay to spread the word about the holiday.

It should be noted that some may find Dewey Decimal System Day a controversial observance because of Melvil Dewey’s history of sexual harassment, racism, and antisemitism. However, a lot of people think it’s possible to separate an invention from its inventor and celebrate the former while acknowledging the latter’s faults.