What are the differences between TCP and UDP protocols?

The most significant differences between TCP (Transmission Control Protocol) and UDP (User Datagram Protocol) are:

1. Connection Establishment:

   • TCP is connection-oriented, establishing a connection via a three-way handshake before data transfer.
   • UDP is connectionless, sending data without prior handshake.

2. Reliability:

   • TCP guarantees delivery, order, and retransmission of lost packets.
   • UDP does not guarantee delivery, order, or retransmission.

3. Flow and Congestion Control:

   • TCP has mechanisms for flow control and congestion control.
   • UDP has no built-in flow or congestion control.

4. Speed:

   • TCP is slower due to overhead from connection management and reliability features.
   • UDP is faster with less overhead.

5. Header Size:

   • TCP header is 20-60 bytes.
   • UDP header is 8 bytes.

6. Use Cases:

   • TCP is used for applications requiring reliable delivery (HTTP, FTP, SSH, SMTP).
   • UDP is used for applications where speed is critical and some data loss is acceptable (DNS, DHCP, streaming, gaming, VoIP).

Feature	TCP	UDP
Protocol Type	Connection-oriented	Connectionless
Reliability	Reliable	Unreliable
Delivery Order	Guaranteed	Not guaranteed
Retransmission	Yes	No
Flow Control	Yes	No
Congestion Control	Yes	No
Speed	Slower	Faster
Header Size	20-60 bytes	8 bytes
Examples	HTTP, FTP, SSH	DNS, VoIP, Gaming

This overview highlights the fundamental differences, guiding the choice based on application needs.