Open Graph metadata
book:release_date
Records when a book was released. Open Graph defines the value as an ISO 8601 datetime.
Code examples
Good example
<meta property="book:release_date" content="2026-07-04">An ISO 8601 calendar date when no exact release time is needed.
Good example
<meta property="book:release_date" content="2026-07-04T00:00:00-04:00">A release datetime with an explicit UTC offset.
Avoid this example
<meta property="book:release_date" content="July 4, 2026">Readable to people, but outside the ISO 8601 syntax Open Graph specifies.
Avoid this example
<meta property="book:release_date" content="07/04/2026">The day and month order is ambiguous.
Recommendations
- 01Use ISO 8601 FormatUse a complete ISO 8601 value that matches the known precision of the release.
- 02Include TimezoneWhen you include a time, add a UTC marker or offset so the instant is unambiguous.
Related documentation
Related meta tags
book:author
propertyLinks a book to an author profile. The value is a URL, and you can repeat the property for multiple authors.
<meta property="book:author" content="https://example.com/authors/margaret-atwood">Points to the author’s profile page.
book:isbn
propertyProvides the book’s International Standard Book Number as a string.
<meta property="book:isbn" content="9783161484100">A valid ISBN-13 written without display separators.
book:release_date
propertyRecords when a book was released. Open Graph defines the value as an ISO 8601 datetime.
<meta property="book:release_date" content="2026-07-04">An ISO 8601 calendar date when no exact release time is needed.
book:tag
propertyAdds a tag word or phrase associated with a book. Repeat the property to provide more than one tag.
<meta property="book:tag" content="Science Fiction">A clear genre for the book.