The objective of this article is to present a review of the literature relating to the phenomenon of outsourcing as part of the supply chain management approach. We shed light on the different definitions of outsourcing, as well as on the explanatory theories of the phenomenon of outsourcing. It will also be necessary to dwell on the concept of "supply chain" and trust, which makes it possible to understand the link between the phenomenon of outsourcing and the emergence of logistics service providers "LSP