Within a library collection, materials are typically organized
by subject. Librarians assign a call number based on a work's
subject and sources are then shelved by that call number so that
anyone browsing the shelves will find most of the titles on a
subject together. There are 2 main subject classification
systems that translate a work's subject and author or title into
a code (call number) that determines where it will be shelved.
The examples below illustrate how the two main subject
classification systems, Library of Congress and Dewey Decimal,
are used to assign call numbers for the book, Battle in Seattle
by Janet Thomas, published in 2000, about the demonstrations
during the WTO summit in Seattle. Library of Congress: Used in
most college, university, and research libraries because it
handles Dewey Decimal: Used in most public and school libraries
because it is more effective for smaller