UDP, User Datagram Protocol, is a transfer protocol, an alternative to TCP.
Its main difference from TCP is that it’s connectionless.
This implies that it’s faster, each packet sent is more lightweight, as it does not contain all the information needed in TCP, and it does have a lighter handshake process.
The drawback is that UDP is not reliable as TCP.
In TCP, if a packet gets lost, the protocol is able to handle it and the packet is re-sent.
In UDP, this is not built-in into the protocol, and must be handled at a higher level (built on top of it). There is no built-in check to control if a packet was received, and if it is received correctly.
UDP was defined in RFC 768 in 1980.
Some of the most notable application protocols that rely on the UDP layer are DNS and DHCP, and more importantly is the base layer of HTTP/3, the next version of HTTP.
The UDP protocol uses ports to allow communication between processes, like with TCP.
More network tutorials:
- Introduction to WebSockets
- How HTTP requests work
- The HTTP Request Headers List
- The HTTP Response Headers List
- HTTP vs HTTPS
- What is an RFC?
- The HTTP protocol
- The HTTPS protocol
- The curl guide to HTTP requests
- Caching in HTTP
- The HTTP Status Codes List
- What is a CDN?
- The HTTP/2 protocol
- What is a port
- DNS, Domain Name System
- The TCP Protocol
- The UDP Protocol
- An introduction to REST APIs
- How to install a local SSL certificate in macOS
- How to generate a local SSL certificate
- How to configure Nginx for HTTPS
- A simple nginx reverse proxy for serving multiple Node.js apps from subfolders
- What is a reverse proxy?