Last Modified
The last modified date is a response typically contained within a sitemap file and is used to inform search engines when a page was last updated. This can be used to encourage a search engine to re-crawl a page faster due to the content being seen as updated. As Google place high importance on the last modified date within an XML sitemap, our SEO Office Hours Notes cover further advice and recommendations around the use of last modified dates on your website.
Last Modified In Sitemaps Aids Crawling
Google thinks the Last Modified date in an XML Sitemap can be very useful to help them recrawl URLs, and they also support RSS and Atom feeds.
Change Frequency and Priority in Sitemaps Are Ignored
Change Frequency and Priority in XML Sitemaps are not used by web search, but the lastmod date is used.