A sitemap is a file that lists the URLs of a website in a format readable by crawlers. This file, most often in XML format, conveys to search engines the list of pages to crawl and index. Its role is not limited to a simple inventory: the way it is constructed, maintained, and submitted directly affects the speed and quality of indexing.
Lastmod tag in an XML sitemap: why its reliability changes everything
Most guides on sitemaps mention the lastmod tag as an optional attribute. In practice, this tag has become an operational signal for Google and Bing.
The principle is simple: lastmod indicates the date of the last substantial modification of a page. Crawlers use it to prioritize their crawl. A page whose lastmod date has changed will be re-crawled more quickly than a page whose date remains stable.
The problem arises when the date is incorrect. Some CMS or generation scripts automatically update all lastmod dates with each deployment, even without any actual content modification. A change in footer, template, or copyright notice does not constitute a substantial modification. A misleading lastmod date eventually gets ignored by search engines, which nullifies the purpose of the sitemap for prioritized crawling.
For lastmod to remain reliable, the date should only change when user-visible content has actually been modified: text, images, structured data. The resources available on the site www bargento fr illustrate well the structure of a properly formatted sitemap with consistent dates.
Sitemap and crawl budget: what the XML file really controls
The XML sitemap does not guarantee indexing. A file correctly retrieved by Googlebot does not mean that all listed URLs will be indexed. The sitemap acts as a suggestion, not as a directive.
Its real usefulness concerns the crawl budget. On a large site, crawlers have a limited time to explore pages. The sitemap allows them to discover URLs that are not accessible via internal linking or that are several levels deep.
This is precisely why the content of the sitemap must be filtered. Including non-indexable pages (noindex), 301 redirects, canonicalized URLs to other pages, or error pages wastes crawl on unnecessary resources.
- Each URL in the sitemap must return a HTTP 200 code and be indexable.
- Pages with a canonical tag pointing to another URL do not belong in the file.
- URLs blocked by the robots.txt file should not appear in the sitemap, as the crawler will not be able to explore them.
- Pagination, filter, or internal sorting pages are rarely relevant candidates.
A streamlined sitemap with only useful URLs improves indexing coverage much more than a comprehensive file that drowns strategic pages among thousands of secondary URLs.
Submitting the sitemap in 2026: deprecated ping and alternatives
For years, the standard method to notify Google of a new sitemap involved sending an HTTP request to a notification endpoint (the “ping”). This method has been deprecated by Google, which no longer recommends it as a reliable submission channel.
The two channels that remain operational are declaration in the robots.txt file (via the Sitemap: directive) and direct submission in Google Search Console. The Search Console offers an additional advantage: it returns status reports indicating how many URLs have been discovered, how many are indexed, and which ones have issues.
IndexNow as a complement for Bing
On the Bing side, the IndexNow protocol allows for real-time notification of URL creations, modifications, or deletions. This protocol does not replace the sitemap but complements it. The sitemap remains the basis for the overall discovery of pages, while IndexNow accelerates the consideration of specific changes.
This combination of sitemap plus IndexNow proves particularly suitable for sites with frequently changing content: news sites, marketplaces, product catalogs updated daily.
Sitemap index and segmentation for large sites
The sitemap protocol imposes a double limit per file: a maximum number of URLs and a maximum size. When a site exceeds these thresholds, the technical solution is the sitemap index, a file that references multiple child sitemaps.
Segmentation should not be arbitrary. Grouping URLs by content type (articles, product sheets, categories, institutional pages) allows for monitoring the indexing of each segment in the Search Console. If a child sitemap dedicated to product sheets shows a low indexing rate, the diagnosis is immediate: the problem lies with that type of content, not the site as a whole.
- One sitemap per content type facilitates tracking in Google Search Console.
- Specialized sitemaps (images, videos) enrich media indexing with dedicated metadata.
- The news sitemap (Google News) meets specific freshness constraints, with URLs that remain relevant for only a few days.
This segmented approach transforms the sitemap from a simple technical file into a true SEO diagnostic tool.
The sitemap remains an underestimated lever because it seems simple to implement. The difference between a default-generated file and an optimized, filtered, segmented, and properly submitted sitemap is directly measurable in indexing coverage reports. A well-maintained sitemap reflects the actual structure of the site you want to make visible.
