Question

What is the purpose of the sequence number field in the TCP header?

Answer 1

Answer:

TCP Sequence number wrap around concept it's segment consists of a TCP header, TCP options and the data that the segment transport.

Sequence number the 32 bit sequence number field defines the number assigned to the first byte of data contained in this segment

TCP is a stream transport protocol.

Answer 2

Answer:

The TCP header contains the sequence number of the first byte in this segment. TCP packets can contain an acknowledgement, which is the sequence number of the next byte the sender expects to receive (and thus, an acknowledgement of receiving all bytes prior to that).