What is special about TCP protocols?

TCP (Transmission Control Protocol) protocols:

• Reliability: Ensures guaranteed delivery of data. Packet losses are detected and retransmitted.
• Stream-oriented: Considers data as a continuous stream of bytes rather than a set of individual messages.
• Order of delivery: Guarantees that packets are delivered in the order they were sent.
• Flow control: Regulates the rate of data transmission to prevent overwhelming the receiving device.
• Congestion control: Adapts to network conditions to avoid congestion.
• Connection establishment (three-way handshake): A logical connection is established before data transfer between sender and receiver.

// Example of establishing a TCP connection (simplified)
// Client sends SYN
// Server responds with SYN-ACK
// Client responds with ACK

• Connection termination (four-way handshake): The connection is properly closed.
• Full-duplex communication: Data can be transmitted in both directions simultaneously.

Comparison table with UDP (User Datagram Protocol):

Characteristic	TCP	UDP
Reliability	Guaranteed delivery	Not guaranteed
Order	Guaranteed order	Not guaranteed
Flow control	Present	Not present
Congestion control	Present	Not present
Connection-oriented	Yes	No
Headers	Larger overhead	Smaller overhead
Speed	Slower (due to reliability)	Faster (no control)
Applications	HTTP, FTP, SSH, Email	DNS, DHCP, VoIP (some)