TCP Header

Source Port: Port number of the sender

Destination Port: Port number of the receiver

Sequence Number: The amount of data sent during the TCP session (3 way handshake)

Acknowledgement Number: The receiver asks for the the next TCP segment once it has received the initial segment along with the sequence number

DO:  Data offset also known as TCP header length. It tells us the total length of the TCP header and where the data begins

RSV:  Reserved field which is barely used

Flags:  Used for establishing terminating connection and for sending data

Window: The receiver will let the sender know how much data it can receive in bytes

Checksum: Used to check for any errors on the TCP header

Urgent Pointer: Indicates where the urgent data ends