If an ecommerce business doesn't have their own warehouse, what other options are available?

Not all ecommerce businesses can afford to invest on having a warehouse. So what other budget friendly and efficient options are available to manage the entire inventory movement smoothly? Any examples are appreciated. 

kswck22020-09-18T12:25:16Z

That is what 'Partners' are for. That is why Amazon is so successful. Do you really think that every item the goes through Amazon is stored in their own warehouse? Of course not. Some items are in other warehouses and shipped from there.