Breadcrumbs are a navigational aid that allow users to keep track of their location within programs, documents or websites. They align to the design heuristic of Sense of Place, where users should know where they are right now and how to get back to where they started from.
Generally, breadcrumbs consist of a delimited list of links starting with the homepage (or one link below the homepage, as it's generally accessible through the global masthead) and working its way down the site architecture to the existing page.
When to use
If the user cannot navigate directly back to the parent of the existing page using the global masthead, breadcrumbs should be applied. Or in short, anything more than 2 levels down in the navigation structure.
When not to use
- Don't use breadcrumbs for navigation on a page that's already in the masthead navigation.
- Don't use breadcrumbs on dialogs.
- Last one Only Breadcrumbs by Brad Frost outlines a breadcrumb solution that only exposes the last item in the trail by default but exposes the entire trail when space becomes available.
- Breadcrumbs in Web Design: Examples and Best Practices by Jacob Gube on Smashing Magazine outlines best practices and shows a set of examples of well-designed breadcrumbs