The Library of Congress Control Number (LCCN) is a system-catalogued records in the Library of Congress. Libraries use the designated number to locate specific Library of Congress catalogue records in the national database and for other administrative necessities.
Because of the number of books the Library of Congress must review each year (which is literally hundreds of thousands), it is highly unlikely that a self-published book will be chosen to be added. Some authors, however, like to include the LCCN because it adds credibility to their book.
The Library of Congress also utilizes two, mutually-exclusive systems called CIP Publishers and PCN Publishers. CIP Publishing is not available for self-published or print-on-demand books.
Authors/self-publishers may, however, use the Prepub Book Link’s author/self-publisher portal to apply for the program and submit an application for an LCCN.