For the most part, warehouses are commonly managed through the ERP and not the Admin Console. However, the Admin Console does provide a wide variety of customizations and control. Warehouses allow you to manage the inventory of the products available on your website. A warehouse can either be a physical or a logical segregation of inventory. Using multiple warehouses allows for the identification of a default warehouse for products to come from, as well as the assignment of alternate warehouses that also carry the same product.
It can be advantageous for many reasons to use multiple warehouses to manage the inventory of products. For a physical example, a company has two warehouses: Warehouse One is the default warehouse, and Warehouse Two is the alternate. Because you know most of your customers are closer to Warehouse One and only a few are closer to Warehouse Two, you decide to keep 300 units of Product A in Warehouse One and 100 units of Product A in Warehouse Two. The website will show 400 total units of Product A, but to benefit your customers, you can assign the warehouse that is closer to a specific customer to keep shipping costs down. Another example using logical segregation would be to keep like products in like warehouses. If you are a construction supply company, it may make sense to keep lumber, electrical, roofing, and so on each in their own respective warehouses.
A warehouse cannot be assigned to itself as an alternate, thus the available warehouses list only displays warehouses that are not already assigned as alternates.
Video: Warehouse overview