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What is UDP?

When speed matters more than making sure every piece of data arrives, the internet uses UDP.

UDP, or User Datagram Protocol, is a way of sending data across a network without waiting for confirmation that it arrived. Unlike TCP, which checks that every packet is delivered and requests replacements for anything that goes missing, UDP sends data and moves on, with no handshake, no verification, and no re-sending.

Importantly, that’s not a flaw. For certain applications, it’s exactly the right approach. Video calls, live streams, and online gaming all rely on UDP because they need information to arrive fast and in sequence. If a few packets get dropped during a video call, a brief blip in quality is far less disruptive than freezing while the connection waits to recover missing data. 

UDP is also used behind the scenes for things like DNS lookups, where requests are small and speed is a priority.

There is a tradeoff, of course. For anything where accuracy is non-negotiable, like loading a webpage or downloading a file, TCP is the better fit. UDP is a tool for situations where getting there fast is worth the occasional imperfection.