Describe the process of establishing a TCP connection and the three-way handshake.

The process of establishing a TCP connection involves a three-way handshake between the client and the server. This handshake is a series of steps that ensures both parties are ready to communicate and establishes a reliable connection.

1. Step 1: SYN (Synchronize)
The client initiates the connection by sending a TCP segment with the SYN (synchronize) flag set to the server. This segment contains a sequence number that the client chooses randomly. This sequence number is used to keep track of the order of the segments exchanged between the client and the server.

2. Step 2: SYN-ACK (Synchronize-Acknowledge)
Upon receiving the SYN segment, the server acknowledges the request by sending a TCP segment with both the SYN and ACK (acknowledge) flags set. The server also generates its own random sequence number and includes it in the segment. The ACK flag indicates that the server has received the client's SYN segment and is ready to establish a connection.

3. Step 3: ACK (Acknowledge)
Finally, the client responds to the server's SYN-ACK segment by sending an ACK segment. This segment acknowledges the server's response and completes the three-way handshake. The ACK segment also includes an incremented sequence number, indicating that the client is ready to start sending data.

At this point, the TCP connection is established, and both the client and the server can start exchanging data. The sequence numbers exchanged during the handshake are used to ensure that the segments are delivered in the correct order and to detect any lost or duplicate segments.

It is important to note that the three-way handshake is a fundamental part of TCP's reliability mechanism. It guarantees that both parties are ready to communicate and establishes a reliable connection before any data transmission occurs.