What happens during a graceful TCP session closure?

During a graceful TCP session closure, the connection termination process involves the exchange of FIN and ACK flags. When one side of the connection wishes to close the session, it sends a FIN (finish) segment to the other side to indicate that it has finished sending data. The receiving side acknowledges this request by sending an ACK (acknowledgment) in response, confirming that it has received the FIN segment. This two-step process ensures that both parties agree to terminate the connection cleanly and that any remaining data can be properly transmitted and acknowledged before the connection is completely closed.

This method contrasts with other approaches where connections might be terminated abruptly, such as by sending a reset (RST) flag, which does not allow for a proper exchange of final data or acknowledgments, potentially leading to data loss or inconsistencies. A graceful closure preserves the integrity of the session and ensures that both ends of the communication are synchronized before they disconnect.