Which mechanism allows for programs running on a server (daemons) to listen for requests through the process called binding?

When a daemon or server process starts, it binds to a port number on which to listen for a request. An example is a web server binding to the port number of TCP/80. A port is communicated in the header of TCP and UDP segments, but the header does not listen for requests or bind. MAC addresses are physical locations on a local area network (LAN) that are used to transmit framed data. Checksums are used to verify that data are not erroneously modified in transit.