A breadcrumb, or breadcrumb trail, is a navigational aid that is typically placed between a site's header and the main content, displaying either a hierarchy of the current page in relation to the the site's structure, from top level to current page, or a list of the links the user followed to get to the current page, in the order visited.
A location breadcrumb for this document might look something like this:
Breadcrumb trails enable users to be aware of their location within a website. This type of navigation, if done correctly, helps users know where they are in a site and how they got there. They can also help a user get back to where they were before and can reduce the number of clicks needed to get to a higher-level page.