Date the content expires and is no longer useful or available. For example a [VideoObject](https://schema.org/VideoObject) or [NewsArticle](https://schema.org/NewsArticle) whose availability or relevance is time-limited, a [ClaimReview](https://schema.org/ClaimReview) fact check whose publisher wants to indicate that it may no longer be relevant (or helpful to highlight) after some date, or a [Certification](https://schema.org/Certification) the validity has expired.
