What is the Difference Between UDP and TCP?

1. Connection:

   • TCP is connection-oriented. It establishes a connection before data transmission, involving a three-way handshake process to ensure both parties are ready for data transfer.
   • UDP is connectionless. It does not require a prior connection; data can be sent directly to the recipient without waiting for a connection to be established.

2. Reliability:

   • TCP provides reliable data transmission through mechanisms such as sequence numbers, acknowledgment, retransmission control, flow control, and congestion control, ensuring data accuracy and order.
   • UDP does not guarantee reliable data transmission. Data packets may be lost or arrive out of order, and it lacks built-in mechanisms to correct these errors.

3. Speed and Efficiency:

   • TCP is typically slower than UDP due to its mechanisms for ensuring data accuracy and order. These mechanisms make TCP highly reliable but also increase communication overhead.
   • UDP offers faster data transmission speeds due to the absence of complex control mechanisms, making it suitable for applications with high real-time requirements, such as video conferencing and online gaming.

4. Data Stream:

   • TCP provides a stream-oriented service. Data transmitted over a TCP connection is sent as a byte stream, and the receiver receives data in the order it was sent.
   • UDP provides a datagram service. Each UDP user datagram is transmitted independently, with a well-defined boundary for each datagram.

5. Header Overhead:

   • TCP has a larger header overhead than UDP. The TCP header is at least 20 bytes, containing information for reliable transmission.
   • UDP has a small header overhead, only 8 bytes, making it suitable for transmitting small amounts of data.

6. Use Case Examples:

   • TCP is commonly used in applications such as web browsing (HTTP/HTTPS), email (SMTP/POP/IMAP), and file transfer (FTP), which require accurate data transmission.
   • UDP is often used for streaming media (e.g., video and audio streams), online gaming, and voice calls (VoIP), where speed is prioritized over the integrity of individual data packets.

In summary, TCP and UDP each have their own advantages and disadvantages, suitable for different network scenarios. TCP ensures data reliability through complex mechanisms, making it ideal for applications requiring high reliability. UDP, with its low-latency characteristics, is suitable for applications needing fast data transmission but can tolerate some data loss.