Breadcrumbs are a useful tool for letting your users know where in your site they are. At the top of each page, you present your users a series of links allowing them to go back up to a parent section.
As an example, let’s say you have a food blog. One of the categories of that blog is French recipes. You then have a sub-category named Southern French and in there the recipe for an amazing cassoulet, a typical southern French casserole. When your users open the Cassoulet recipe, at the top of the post the will see something like the following.
Your users can quickly see your Southern French recipes as well as the highest category of French recipes.
The benefit of this feature is that it gives your users a sense of comfort and familiarity as they always know where they are.