John Mueller from Google explained on Twitter the difference between the timestamp date in an XML Sitemaps lasmod date and the date on a web page. John said the sitemaps lastmod is when the page as a whole was last changed for crawling/indexing. The date on page is the date to be associated with the primary content on the page.
John Mueller first said "A page can change without its primary content changing." He said that doesn't think "crawling needs to be synced to the date associated with the content." The example he gave was for "site redesigns or site moves are pretty clearly disconnected from the content date."
He then added this tweet:
Correct! Sitemaps lastmod = when the page as a whole was last changed for crawling/indexing, date on page = date to be associated with the primary content on the page. They can be the same, but don't need to be.
— 🍌 John 🍌 (@JohnMu) April 24, 2019
So there you have it.
Forum discussion at Twitter.
