Two ways by which TCP uses the sequence numbers when it comes within a segment are:
1. for the identification of the segment that might be missing at the destination.
2. for reassembling the segments when it comes to the remote location.
The acknowledgment fields and sequence happen to be just two of several features through which we can TCP as a connection-oriented protocol. However, when a TCP connection helps to serve as a medium for the transfer of data, the assist the remote host in keeping track of the connection and also make sure that there is no loss of packet on its way to its destination.
TCP makes use of positive acknowledgments, retransmissions, and timeouts to achieve a sequenced delivery of user data that is error-free. In addition, it is important to be aware of the fact that each operating system generates its sequence numbers differently.