A sitemap is a file that lists the URLs of a website and presents them hierarchically to search engine bots. Google, Bing, and other crawlers use it to discover pages, but also to obtain metadata about each page (last modified date, update frequency, relative priority).
The presence of a sitemap does not guarantee the indexing of all listed pages: it is a discovery signal, not an order given to the engines.
The lastmod field in an XML sitemap: a technical detail often misused
Most guides on sitemaps focus on creating the file and submitting it. One aspect rarely covered in depth is the <lastmod> field, which indicates the last modified date of a URL.
Google specifies that this date is only considered if it reflects a real and significant change to the page. Automatically regenerating the sitemap every night, without any content changes, produces misleading dates. The bot eventually ignores this signal, which reduces the usefulness of the file.
For an XML sitemap to remain reliable, the lastmod date must correspond to a real change in content. If you are using a CMS like WordPress with an SEO plugin (Yoast, SEO Press, Rank Math), ensure that the sitemap regeneration is triggered by the publication or update of a post, and not by a daily cron unrelated to the content.
This point of vigilance also applies to e-commerce sites where product listings frequently change in price or stock. Updating the date only when the descriptive text or images change helps maintain a consistent signal for crawlers. On La Top Liste’s sitemap page, this targeted update logic is visible: only modified URLs appear with a recent date.
XML sitemap and HTML sitemap: two files for two distinct audiences
An XML sitemap is aimed at crawling bots. It is written in a structured format that humans do not consult directly. An HTML sitemap, on the other hand, is a page on the site accessible to visitors, listing sections and articles as clickable links.
The XML sitemap helps engines discover your pages, while the HTML sitemap facilitates navigation for lost users or those arriving on a dead-end page. Both serve complementary functions.
When the HTML sitemap remains relevant
On a site with just a few dozen pages, an HTML sitemap may seem unnecessary. It makes perfect sense on large sites (editorial portals, directories, catalogs) where internal linking is not sufficient to make all pages accessible within three clicks from the homepage.
A well-designed HTML sitemap acts as a safety net for orphan pages, those URLs that receive no internal links and that crawlers struggle to find. If your structure has deep sections or categories rarely highlighted in the main menu, a HTML page listing these URLs improves their accessibility.
Structure of the XML file: the tags that matter for SEO
The Sitemap protocol defines several tags. Not all carry the same weight in practice.
<loc>contains the full URL of the page. It is the only mandatory tag. Each URL must be absolute (starting with https://) and exactly match the canonical address of the page.<lastmod>indicates the date of the last significant modification. As mentioned earlier, it must reflect a real change to be considered by Google.<changefreq>suggests an update frequency (daily, weekly, monthly). Google has stated that it does not take this tag into account, making it largely cosmetic.<priority>assigns a relative priority value between pages of the same site. Again, its real influence on crawling is limited, if not null on Google’s side.
Only the loc and lastmod tags have a verifiable impact on the behavior of bots. Filling out changefreq and priority meticulously does no harm, but does not provide measurable benefits.
Extensions for images, videos, and news
Google documents extensions of the XML format to signal specific content. A sitemap can include tags dedicated to images (<image:image>), videos (<video:video>), or news articles (<news:news>).
These extensions provide bots with additional information (image caption, video duration, publication date of an article). For a site that regularly publishes multimedia content, sitemap extensions enhance visibility in Google Images and Google Videos.
Submitting and monitoring a sitemap: beyond Google Search Console
Submitting a sitemap via Google Search Console is the most documented method. You provide the URL of the file (usually yoursite.com/sitemap.xml), and Google takes care of it during its next crawls.
A lesser-known aspect: Bing offers a complementary channel called IndexNow. This protocol allows notifying participating search engines as soon as a URL is added, modified, or deleted, without waiting for the bot to come back and crawl the sitemap. IndexNow speeds up the consideration of changes for engines that support it (Bing, Yandex, among others).
The sitemap as a diagnostic tool
Submitting a sitemap is not only for discovery. In Bing Webmaster Tools as in Google Search Console, the coverage report compares the URLs submitted via the sitemap to the URLs actually indexed. This gap reveals concrete issues:
- Pages blocked by the robots.txt file while they appear in the sitemap
- URLs returning 404 errors or chain redirects
- Pages deemed low quality by the engine and excluded from the index despite their presence in the file
Comparing submitted URLs to indexed URLs helps identify problematic pages before they affect the overall visibility of the site. A well-structured sitemap then becomes both a monitoring tool and a discovery tool.
A sitemap remains an auxiliary file. It does not fix a faulty internal linking structure or thin content that does not deserve indexing. Its role is to facilitate the work of bots and provide you with a clear control point over your site’s coverage. Keeping it up to date, with reliable dates and clean canonical URLs, is enough to make the most of it.
