The copyright date in a book typically indicates the year in which the author or owner of the information filed intellectual and media copyrights for the material. The first date listed is the first edition or form protected by the author or owner. Each subsequent year indicates updates and revisions.
The copyright date and published date are often the same, but not always. Publishing a book in a certain year does not mean the date of the copyright is also in that year. The author of the book or owner of the material in a book may have filed a copyright on the material without publication.