When surfing the web and researching online privacy, you’ll probably have encountered the acronym UDP. But what is UDP, what does it stand for and why is it something ordinary people need to know about?

UDP stands for User Datagram Protocol, which probably doesn’t clear up the question what is UDP for many readers. So a quick guide to the ins and outs of it might be handy to give UDP a meaning in your digital activity.

Getting started with a basic UDP definition

It makes sense to start with a simple UDP definition. Basically, it is a protocol used on networks, whether they are local or global.

By protocol, we mean a set of rules which govern how computers or other devices interact. Without them, networks wouldn’t be able to authenticate which users are sending and receiving data, and the internet would be a free-for-all. In other words, the UDP protocol helps to keep the online world running.

UDP isn’t just any old protocol. It’s an important alternative to a more famous protocol called TCP (Transmission Control Protocol), which is ubiquitous across the web.

Understanding how TCP and UDP differ

Both TCP and UDP act as layer protocols on top of IP (Internet Protocol), which is universally used to connect online users together. This allows data to be sent between two IP addresses, and it’s the reason why you’ll see both referred to as UDP/IP or TCP/IP. But that’s where the similarities end.

In TCP transmissions, computers communicate by sending and receiving “packets” of data, which have to be authenticated before acceptance. Like parcels in a distribution network, these packets are checked before delivery and they are also numbered to ensure that data arrives in the proper form.

With the UDP protocol, things are slightly different. As you’ll probably have guessed from the UDP meaning above, this protocol uses “datagrams” to send information. These are like packets, but have an important property: when datagrams are sent, they aren’t authenticated or checked along the way. This tends to make UDP faster, if less reliable than TCP/IP.

What makes it a “connectionless” protocol

You might also see UDP described as “connectionless”. So what does this mean? What is UDP without connection? Again, this is best understood by comparing UDP with TCP.

TCP is a connection-oriented protocol. By this, we mean that data packets sent using TCP can only be transmitted if a connection is established between the sender and receiver. This is what allows the two computers to authenticate the data being sent.

With UDP, this connection isn’t established, which is why we call it connectionless. Data is funneled through a number of UDB servers from A to B, without a direct connection between the two.

When we asked “what does UDP stand for” we mentioned that the D stood for the datagram. That’s because data packets sent via connectionless protocols are always known as datagrams – something that is worth keeping in mind as you start to use VPNs regularly.

What is UDP used for?

Now we know a bit more about what is UDP and we have a basic UDP definition, but what is it used for in the real world? Surely, with its weaker authentication processes, it would be less desirable than TCP for most data transmission purposes?

Well, actually that’s not necessarily the case. The beauty of UDP is that it doesn’t require what is known as “congestion control” it just streams into your computer with no obstructions, and no need to devote resources to checking every packet as it arrives.

This makes UDP networking a popular option for professional gamers (and it’s commonly used at E-sports events, for example). But it’s also used in situations where constant streams of accurate information are needed, from the flow of weather data to fluctuations in the prices of stocks and shares.

With currency traders now relying on micro-second advantages to get ahead of the pack, the financial sector is a heavy user of UDP, so it’s not an also-ran. It’s a vital part of the internet’s infrastructure.

How does UDP networking work?

As with all networking systems, UDP has to be connected to a specific UDP port before it can be used. Ports are linked to your IP address, and they act like your mailbox in real life – allowing data to arrive at your location or leave for distant UDP servers.

Different protocols have different port numbers assigned to them, but TCP and UDP can override many of these protocols and use a wide variety of ports to establish online connections. It’s not really practical to list them all here, but you can find plenty of lists of available UDP port online if you want to learn a little more.

Can UDP servers be used with VPNs?

If you’re a Virtual Private Network user and want to mix fast data transmission with anonymity and security, this will be the billion dollar question. Most VPN providers offer TCP and UDP as options on their servers, so it’s a question that many people face, even if they don’t have the technical background needed to work out the right answer.

Remember what we talked about when we asked: what is UDP? We mentioned that the major difference between the two protocols boils down to one thing: speed.

So you’ll probably benefit from using a UDP port for VPN networking if your internet activity revolves around streaming. If you use online gaming platforms, want to use your VPN to work around Netflix geo-blockers, or use Voice Over IP services heavily, the UDP protocol will most likely work best.

The best option for live streaming?

Yes, if you are a heavy user of streaming sites like Twitch, YouTube or Netflix, you’ll probably experience better performance when you use UDP as opposed to TCP/IP.

There are a number of good reasons for this. However, above all, UDP offers much lower latency rates than TCP (most of the time). That’s because packets being received by your system aren’t authenticated before receipt. If packets are sent back by TCP, they can result in serious congestion, slowing down or breaking streams entirely.

However, there are some qualifications to mention regarding streaming. If you use UDP regularly, you might notice some image corruption and a loss of quality. If data isn’t checked as it arrives, corrupt data is accepted along with clean packets, and this can affect the quality of both audio and visuals.

So if you’re more concerned with picture quality than smooth transmission, it might be a good idea to try TCP instead of UDP networking.

What about security? Is a UDP connection safe?

When we ask what is UDP used for, one answer that rarely arises is “keeping data safe in transit.” That’s because TCP is generally seen as a more secure option, whether you use VPNs or not.

Why is this? TCP is less vulnerable than UDP to what is known as “packet forging”. When data packets arrive via TCP, the protocol has to authenticate them and send this authentication signal back to the sender before the data can be used.

With UDP, there is no authentication. This means that cyber-criminals or surveillance agencies could easily intercept your stream of data, forging an IP address to gain access to your internet traffic.

Moreover, because UDP is a connectionless protocol, firewalls tend to intercept the data sent via UDP meaning that it can be hard to put in place measures to compensate for the protocol’s security shortcomings.

For these reasons, many experts recommend that VPN users switch from a UDP port to TCP/IP when sending confidential messages or networking in repressive countries. UDP may have speed advantages, but its security risks are very real.

Summary: the advantages and disadvantages of UDP protocol

Now is probably a good time to sum up the pros and cons of using a UDP connection, so that you can make an informed decision the next time you fire up your VPN.

First the pros:

  • High-speed connections allow for smoother streaming
  • Low overheads due to the lack of authentication processes
  • Networking can be simplified and speed enhanced

And the cons:

  • UDP may be vulnerable to IP address spoofing/packet forging
  • Users cannot guarantee that data will be delivered
  • Data may be corrupted before arrival with no means of authentication

Experiment and speed up your VPN experience

UDP is one of the most important tools available to VPN users, and it’s a commonly used protocol on almost all major VPN providers. As we’ve seen, it’s generally fast and handy for streaming or casting services, but comes with a few inherent problems that are worth thinking about – most notably weaker security.

If you’re using the web to stream entertainment or make video calls, you’ll probably find that UDP is extremely useful, but always remember that it’s not the only option available.