Which function does the transport layer perform in networking?

The transport layer is responsible for delivering data from a sending application to the correct application on the receiving end. It operates above the network layer and is focused on the end-to-end communication between applications. The primary protocols associated with the transport layer, such as TCP (Transmission Control Protocol) and UDP (User Datagram Protocol), facilitate this process by using features like port numbers to distinguish between different applications or services running on a device.

For instance, TCP provides reliable delivery, ordering, and error-checking of data segments, while UDP provides a simpler, connectionless service. Both of these protocols ensure that data is not only sent and received but also appropriately directed to the specific application that needs it, thus fulfilling the transport layer's key function of delivering packets to the correct application.