Contrasting Controlled Vocabulary and Tagging: Experts Choose the Right Names to Label the Wrong Things

Social cataloging sites—tagging systems where users tag books—provide us with a rare opportunity to contrast tags to other information organization systems. We contrast tags to a controlled vocabulary, the Library of Congress Subject Headings, which has been developed over several decades. We find that many of the keywords designated by tags and LCSH are similar or the same, but that usage of keywords by annotators is quite different.