Ποια είναι η διαφορά μεταξύ των πρωτοκόλλων TCP και UDP;

TCP (Transmission Control Protocol):

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

UDP (User Datagram Protocol):

• Unreliable: Does not guarantee delivery, order, or absence of duplicates.
• Without connection establishment: Does not require a "handshake".
• Datagram-based: Data is sent in separate packets (datagrams).
• Fast: Low overhead ensures high speed.
• Applications: DNS, DHCP, streaming audio/video, online games.

Characteristic	TCP	UDP
Reliability	High (guarantees 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 (header checksum only)
Order guarantee	Yes	No
Flow control	Yes	No