Why it matters to a buyer
On a deep catalogue or blog, breadcrumbs are one of the clearest ways a visitor orients themselves without using the back button, and they reinforce the site's category structure for search engines at the same time. For a buyer, breadcrumbs are also a small but visible sign of information architecture done properly: if a site cannot show a clean path from a product back to its category, that usually means the category structure itself is thin or missing, which is a bigger technical SEO issue than the breadcrumb line alone.
How it is measured or applied
Breadcrumbs are built to match the site's real folder structure, one link per level, ending on the current page as plain text rather than a link. Marking them up with BreadcrumbList structured data lets Google show the path instead of the URL in some search results, though this is not guaranteed. They are checked visually on templates across the site and validated with Google's Rich Results Test, and any mismatch between the breadcrumb path and the actual URL or category tree is treated as a sign the site's structure needs cleaning up, not just the markup.
Sources
- Breadcrumb (BreadcrumbList) structured data, Google Search Central
