High Quality Content by WIKIPEDIA articles! The Library of Congress Classification (LCC) is a system of library classification developed by the Library of Congress. It is used by most research and academic libraries in the U.S. and several other countries; for example, Australia and Taiwan, R.O.C. It is not to be confused with the Library of Congress Subject Headings or Library of Congress Control Number. Most public libraries and small academic libraries continue to use the Dewey Decimal Classification (DDC).