What is the primary function of the transport layer in the OSI model?

The primary function of the transport layer in the OSI model is to ensure reliable or unreliable delivery of data and to facilitate error recovery. This layer is responsible for end-to-end communication between devices and provides services such as segmentation of data into smaller units, flow control to manage data transmission rates, and error detection and correction to ensure that data is received accurately.

In contrast to the functions of other layers, the transport layer operates above the network layer, which is focused on routing data between devices through potentially multiple networks. While encryption and security measures can be implemented at various layers, they are not the defining responsibilities of the transport layer. Additionally, the management of the physical connection between devices is handled at the physical layer, which is much lower in the OSI model. Therefore, the transport layer stands out primarily for its role in guaranteeing that data reaches its destination in a correct and orderly fashion, making it essential in networking protocols like TCP and UDP.