The librarian of Congress is the head of the Library of Congress, appointed by the president of the United States with the advice and consent of the United States Senate, for a term of ten years. The librarian of Congress also appoints and oversees the Register of Copyrights of the U.S. Copyright Office and has broad responsibilities around copyright, extending to electronic resources and fair use provisions outlined in the Digital Millennium Copyright Act. The librarian determines whether particular works are subject to DMCA prohibitions regarding technological access protection. In addition, the librarian appoints the U.S. poet laureate and awards the Gershwin Prize for Popular Song.

The Library of Congress (LOC) is a research library in Washington, D.C., that serves as the library and research service of the U.S. Congress and the de facto national library of the United States. Founded in 1800, the library is the United States's oldest federal cultural institution. The library is housed in three elaborate buildings on Capitol Hill. It also maintains a conservation center in Culpeper, Virginia. The library's functions are overseen by the Librarian of Congress, and its buildings are maintained by the Architect of the Capitol. The Library of Congress is one of the largest libraries in the world. Its collections contain approximately 173 million items, and it has more than 3,000 employees. Its collections are "universal, not limited by subject, format, or national boundary, and include research materials from all parts of the world and in more than 470 languages".