Breadcrumb Navigation
Breadcrumb navigation is the row of links near the top of a page that shows where the page sits in the hierarchy of the site, from the home page down to the current one. Each crumb is a link one level up, so a visitor or a crawler can climb the structure without the menu.
The visible trail and the machine-readable copy
The visible trail is an ordered list inside a nav element with an aria-label, the last item marked aria-current="page" and left unlinked. The machine-readable copy is a schema.org/BreadcrumbList block whose itemListElement is a list of ListItems, each with a position, a name and an item URL. Google’s breadcrumb structured data documentation names itemListElement as the one required property and says the trail may be shown in a result in place of the raw URL. The two copies should agree crumb for crumb. This page carries both, and you can read them against each other.
What the trail tells a machine about the page
A fetched page rarely states what kind of page it is. The trail does. Insights, then Glossary, then a term tells a crawler that the document is a definition inside a reference section, and which section it should be filed under; a trail ending in a product name says the page is a leaf in a catalog. For an assistant deciding what it has just fetched and what the parent topic is, that is one of the few explicit statements on the page. It also means every page links upward, so a crawler that lands on a deep page can reach the hub without a sitemap.
A common question
What does a breadcrumb trail tell a machine that the rest of the page does not?
What kind of page it is. A fetched page rarely states its own type, while a trail running from a section down to the current item says that the document is a definition inside a reference section, or a leaf in a catalog, and names the parent topic along the way. For an assistant working out what it has just fetched, that is one of the few explicit statements on the page. The trail also means every page links upward, so a crawler landing deep in a site can reach the hub without a sitemap.
Related terms
Sources
Markup: schema.org/BreadcrumbList and Google’s breadcrumb structured data documentation. No figures on this page.