Final answer:
TCP and UDP use port numbers to track individual conversations between clients and servers, allowing multiple simultaneous network processes on the same host.
Step-by-step explanation:
TCP and UDP, the main transport layer protocols used in networks, utilize port numbers to track multiple individual conversations between clients and servers. This system allows multiple network processes to occur on the same server without confusion, as each process is assigned a unique port number. Port numbers work together with IP addresses, where the IP address identifies the host, and the port number identifies the application within the host.