This document summarizes third-party logistics (3PL) and fourth-party logistics (4PL) providers. It describes that 3PL providers offer services related to transportation, warehousing, inventory management, and order fulfillment. A 3PL may provide warehousing and inventory management depending on a business's needs. A 4PL offers the same services as a 3PL but also completely manages a business's entire supply chain. The document then lists pros and cons of using a 3PL, such as cost reduction through negotiated rates, ability to scale operations up or down as needed, and gaining logistics expertise, but also lesser control over deliveries and potential for larger upfront costs.