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Module 2~9 min

TCP vs. UDP

TCP and UDP are two common ways that data travels across a network, each with a different tradeoff between reliability and speed.

What You'll Learn

  • What TCP is used for
  • What UDP is used for
  • The tradeoff between reliability and speed

TCP: Reliable Delivery

TCP (Transmission Control Protocol) checks that data arrives completely and in the correct order, resending anything that's lost. This reliability makes it ideal for things like loading web pages or sending emails, where missing data would be a problem.

UDP: Speed Over Guarantees

UDP (User Datagram Protocol) sends data quickly without checking that it all arrives, making it faster but less reliable. It's commonly used where speed matters more than perfect accuracy.

Example

Video calls and online games often use UDP: a dropped frame here and there is barely noticeable, but waiting for retransmission would cause noticeable lag.

Key Concepts

TCPUDPReliability

Key Takeaways

  • TCP guarantees reliable, ordered delivery of data
  • UDP prioritizes speed over guaranteed delivery
  • The right choice depends on whether reliability or speed matters more

Knowledge Check

Which protocol is generally used when reliable, complete delivery matters most?

Which protocol is generally used when reliable, complete delivery matters most?