1. TCP is a transport layer protocol used by applications that require guaranteed delivery.
2. The endpoints are defined by an IP address and a TCP port number. TCP works in full duplex mode and has various fields. It provides handling for both timeouts and re-transmission as it follows sliding window protocol.
3. The TCP header is of 20 byte and the format for data delivery is defined as

The control bits are as stated as below:

a) Urgent (URG bit 106): It indicates if we need to use Urgent pointer field or not. If it is set to 1 then only we use Urgent pointer.

b) Acknowledgement (ACK bit 107): It is set when an acknowledgement is being sent to the sender.

c) PUSH flag (PSH bit 108): When the bit is set, it tells the receiving TCP module to pass the data to the application immediately.

d) Reset flag (RST bit 109): When the bit is set, it aborts the connection. It is also used as a negative acknowledgement against a connection request.

e) Synchronize flag (SYN bit 110): It is used during the initial establishment of a connection. It is set when synchronizing process is initiated.

f) Final flag (FIN bit 111): The bit indicates that the host that sent the FIN bit has no more data to send.