TCP vs UDP: Key Differences Explained
When it comes to sending data over the internet, two common protocols are TCP (Transmission Control Protocol) and UDP (User Datagram Protocol). They work differently and knowing how they compare can help you understand which one to use for your specific needs.
TCP (Transmission Control Protocol)
Connection-Oriented: Before sending data, TCP establishes a connection between the sender and receiver. This ensures both sides are ready.
Reliable: TCP guarantees that data will reach its destination. If a packet gets lost it will be resent until the receiver confirms it’s received.
Acknowledgements: Each packet sent through TCP gets an acknowledgment from the receiver.
Header Size: TCP headers are larger (20-60 bytes) due to extra control information.
Protocol Number: TCP’s protocol number is 6.
Speed: Because of its connection setup and retransmissions TCP tends to be slower than UDP.
When to Use TCP?
TCP is ideal when you need reliable data transfer. Examples include:
File Transfers (FTP)
Web Browsing (HTTP/HTTPS)
Emails
UDP (User Datagram Protocol)
Connectionless: UDP sends data without establishing a connection first. It doesn’t wait for the receiver to be ready.
Unreliable: There’s no guarantee that the data will reach its destination, and if packets are lost, they won’t be resent.
No Acknowledgements: UDP doesn’t require confirmation of receipt.
Header Size: UDP has a very small header size of only 4 bytes.
Protocol Number: UDP’s protocol number is 17.
Speed: UDP is faster than TCP because it doesn’t have to establish a connection or handle retransmissions.
When to Use UDP?
UDP works well when speed is more important than reliability. Examples include:
Live Streaming (video, audio)
Online Gaming
DNS Lookups
TCP vs UDP: A Quick Comparison
| Feature | TCP | UDP |
| Connection | Connection-Oriented | Connectionless |
| Reliability | Reliable (guarantees delivery) | Unreliable (no guarantee of delivery) |
| Speed | Slower (due to connection setup) | Faster (minimal overhead) |
| Header Size | 20-60 bytes | 4 bytes |
| Use Cases | File transfers, emails, web browsing | Streaming, gaming, DNS lookups |
Conclusion
TCP is best when you need reliable data transfer (e.g., file sharing, emails, web browsing).
UDP is better for fast, real-time applications where some data loss is acceptable (e.g., live streaming, gaming).
Choosing the right protocol depends on whether you need speed or reliability for your application.