Let's say a visitor lands on the caramel and dark chocolate product category. They might like what they see, but they might want to look at dark chocolate without caramel. 

If you build your site poorly, the user will have to go all the way back to the Shop or home page and then navigate to the parent category.

By default, WooCommerce will add breadcrumbs to your product and category pages. Breadcrumbs show your users how to navigate back to the home or Shop page.

In this example, we see the breadcrumbs Home | Tshirts | Vneck Tshirt. In Storefront, a product page will look something like this:

And a category page will look something like this:

This is controlled entirely by WooCommerce. But it can be modified by your theme. By default, any theme should have breadcrumbs on the product and category pages. But if your theme does something atypical, you might not see them.

If you want to add or customize breadcrumbs, the best way is to add a custom Personal Home Page (PHP) code to your theme.