The main benefit to facets is that they create virtual groupings of products organized by a product property. You don’t need to decide precisely which products to include or exactly how they should be grouped: you need only to create a facet and specify the product properties it uses to organize products, then decide what products it includes based on where in the catalog hierarchy it resides.
Once you define one facet, it is easy to see how you might want to use several facets together, so one facet organizes products by price, for example, and another facet organizes them by manufacturer. When you use multiple facets, consider the following:
What kind of facets work best together?
On your site, do you want facets to work and appear independently of each other or nested in one another?
What products should the facets include and should all facets include the same products?
