A book’s cover can say, in big letters, The Modern Home Library. The title page reads, The Modern Home Library: Organizing, Cataloging, and Caring for a Personal Collection. Both are titles of the same book, but they’re doing different things. The title on the cover reaches out to you across the store counter. The title on the title page tells you what the book is called in a more formal way, and is usually your best resource for a brief citation.
Cover design can sometimes condense information, or rearrange or delete things like subtitle, series title, editor, translator, or other important elements from a formal bibliographic title. It may put a series title in the place usually reserved for the book title itself, and give the actual title a less prominent placement. It may make the name of a famous contributor to a foreword as big as the author’s name. It may place words in that are important for promotion but don’t actually belong in your record, like a quote from a review, an award it received, or a label that says the book has been revised and is a bestseller.
Sometimes the cover and the actual book aren’t in the same state of mind. A publisher might decide to reuse an earlier book cover on a later printing or just add a new dust jacket or put a sticker on it for a special market. The title page and/or the copyright page might tell you more about the actual edition. If your cover says, “new edition,” check the title page or copyright page for any edition statement, date, or revised responsibility note. You shouldn’t turn “advertising copy” into bibliographic information unless the book as it physically exists supports that interpretation.
The same attention is needed for contributors’ names. What happens if your book cover says, “Mara Bell’s Guide to Local History,” while the title page says, “A Guide to Local History, edited by Mara Bell.” The cover design made Mara Bell’s name part of the sales pitch, but now she is identified as an editor, not an author? Or, what if a cover is decorated to show that an illustrator has done illustrations for this particular title, and her name appears near the book title? You should record only the authorship in your record. If you did, you would miss your own searches and get different authority records for different people with the same name.
Try this. Pick out three books with interesting or crowded covers. Before you open them, note what you imagine the title, subtitle, author, edition, and series are. Next, open up each book to the title page and copyright page. Record every difference you find, but don’t say that one way is “wrong.” Ask what each piece of text is used for: identification, design, advertisement, series brand, contributor, or edition? Make a record based on the facts you find in the book.
Once that’s done, compare that record to the closed book once more. Your record should enable a reader to find it if they searched by the words on the cover, but a record shouldn’t be the design or an ad for a resource. It should identify the resource. The important question is not “which words are the biggest” but “which page in the book will tell me what this resource is, who is responsible for it, and which version of it I’m holding?”