For certain businesses, the products may not be kept and shipped out from the same physical address as your store. These products are kept at one or many warehouses for logistic reasons. For example, you sell flowers that are held in the East and West coast warehouses to reduce shipping cost and delivery time. Drop-shipping is another common practice where the physical product is shipped directly from the manufacturer's address and not from your store. Your shipping rule can take into account the warehouse location and charge a different amount based on the transit distance. Similarly, your shipping availability rule can determine if only certain shipping methods are available depending on the warehouse origin (e.g. your East coast warehouse can ship by UPS only).
Furthermore, the shipping origin has important tax implications. In almost every U.S state, you are liable for tax collection based on where the product is shipped from (warehouse address, not your business address) and where it is ship to. Your tax rule can charge a different tax rate based on the warehouse origin. Please see Order splitting for more information on how orders are treated by warehouse.
The Storefront handles warehouse information to help optimize your shipping cost and delivery time while ensuring you are compliant with tax laws. It will also track the inventory by warehouse so you know exactly how many products are available in which warehouse at all times. You must first enable the Warehouse feature under Configuration > General. Please see Warehouse for more information on associating your products to your warehouses.