"A Classification and Subject Index for Cataloguing and Arranging the Books and Pamphlets of a Library" by Melvil Dewey is a library classification system published in 1876. This revolutionary 44-page pamphlet introduced a decimal-based method for organizing books by subject rather than acquisition order. The system uses three-digit numbers with fractional decimals, allowing books to be shelved in relation to similar topics. What began as a modest guide has expanded through 23 editions and now serves 200,000 libraries across 135 countries, fundamentally transforming how libraries organize knowledge. (This is an automatically generated summary.)