What is the difference between TCP and UDP protocols?

TCP (Transmission Control Protocol):

• Reliable: Guarantees delivery of packets, retransmits lost packets, maintains order. Uses acknowledgments and timers.
• Connection-oriented: Requires a "handshake" (three-way handshake) to start data exchange.
• Stream-oriented: Data is transmitted as a continuous stream of bytes.
• Slow: Overhead for connection setup and delivery guarantees makes it slower than UDP.
• Applications: HTTP/HTTPS, FTP, SMTP, Telnet.

UDP (User Datagram Protocol):

• Unreliable: Does not guarantee delivery, order, or duplicate protection.
• Connectionless: Does not require a "handshake".
• Datagram-oriented: Data is sent in separate packets (datagrams).
• Fast: Low overhead ensures high speed.
• Applications: DNS, DHCP, streaming audio/video, online gaming.

Characteristic	TCP	UDP
Reliability	High (guaranteed delivery and order)	Low (no guarantees)
Connection establishment	Yes (three-way "handshake")	No
Data transmission	Stream-based	Datagram-based
Speed	Slower	Faster
Error control	Yes	No (only header checksum)
Order guarantee	Yes	No
Flow control	Yes	No