Bibliography (from Greek βιβλιογραφία, bibliographia, literally "book writing"), as a practice, is the academic study of books as physical, cultural objects; in this sense, it is also known as bibliology (from Greek -λογία, -logia). On the whole, bibliography is not concerned with the literary content of books, but rather the "bookness" of books.
A bibliography, the product of the practice of bibliography, is a systematic list of books and other works such as journal articles. Bibliographies range from "works cited" lists at the end of books and articles to complete, independent publications. As separate works, they may be in bound volumes such as those shown on the right, or computerised bibliographic databases. A library catalog, while not referred to as a bibliography, is bibliographic in nature. Bibliographical works are almost always considered to be tertiary sources.
Bibliographic works differ in the amount of detail depending on the purpose, and can be generally divided into two categories: enumerative bibliography (also called compilative, reference or systematic), which results in an overview of publications in a particular category, and analytical, or critical, bibliography, which studies the production of books. In earlier times, bibliography mostly focussed on books. Now, both categories of bibliography cover works in other formats including recordings, motion pictures and videos, graphic objects, databases, CD-ROMs and websites.
The word bibliographia (βιβλιογραφία) was used by Greek writers in the first three centuries AD to mean the copying of books by hand. In the 12th century, the word started being used for "the intellectual activity of composing books". The 17th century then saw the emergence of the modern meaning, that of description of books.
Citation formats vary, but an entry for a book in a bibliography usually contains the following information:
An entry for a journal or periodical article usually contains:
A bibliography may be arranged by author, topic, or some other scheme. Annotated bibliographies give descriptions about how each source is useful to an author in constructing a paper or argument. These descriptions, usually a few sentences long, provide a summary of the source and describe its relevance.
Bibliographies differ from library catalogs by including only relevant items rather than all items present in a particular library. However, the catalogs of some national libraries effectively serve as national bibliographies, as the national libraries own almost all their countries' publications.