Breadcrumbs are a type of secondary navigation scheme that reveals the users location in a website or web application. They are a graphical control element used as a navigational aid in user interfaces and on web pages, allowing users to keep track and maintain awareness of their locations within programs, documents, or websites. The term "breadcrumb" or "breadcrumb trail" is borrowed from the story of "Hansel and Gretel" where the kids drop a trail of breadcrumbs to trace their way back home.

Breadcrumbs are typically placed in horizontal form under the masthead or navigation of a website. They provide links back to each previous page the user navigated through to get to the current page or, in hierarchical site structures, the parent pages of the current one. Breadcrumb navigation should be regarded as an extra feature and shouldn’t replace effective primary navigation menus.

There are three types of web breadcrumbs: location, attribute, and path-based. Location breadcrumbs are static and show where the page is located in the websites structure. Attribute breadcrumbs show the attributes of the current page, such as the date it was created or the author who wrote it. Path-based breadcrumbs show the path the user took to get to the current page.

Breadcrumbs are used primarily to give users a secondary means of navigating a website. By offering a breadcrumb trail for all pages on a large multi-level website, users can navigate to higher-level categories more easily. Breadcrumbs also reduce clicks or actions to return to higher-level pages instead of using the back button. They improve the overall experience of the user and encourage them to spend more time on your website, reducing drop-offs and bounce rates.

In summary, breadcrumbs are a navigational aid that allows users to keep track of their current location on a website or interface. They provide links back to each previous page the user navigated through to get to the current page or, in hierarchical site structures, the parent pages of the current one. Breadcrumbs are used primarily to give users a secondary means of navigating a website and improve the overall experience of the user.