5G is going to be a big deal.

It’s predicted that over 1.4 billion devices will be running on the fifth-generation network technology by 2025. According to PCMag, you’ll be seeing the first big 5G applications to pop up around 2021 or 2022. Before that, you’ll see wireless carriers mentioning 5G as they compete for space in consumers’ minds.

5G will also make identity resolution — already a difficult issue for marketers — that much more daunting. With people running more connected devices and being able to transition seamlessly from experience to experience (and device to device), it’ll only get harder to keep track of who they are. More on that in a moment.

Let’s start with 5G, and why it’s going to change the game on multiple fronts.

5G will move more data at greater speed. For consumers, this means faster load times, downloads, and less lag. All that is great, but the really cool stuff happens when you think about connected autonomous cars and remote surgery.

These faster speeds will lead to a new class of app experiences. And as bitbar points out, if virtual or augmented reality experiences previously seemed out of reach for certain apps, 5G could change that.

In terms of latency, we’re talking sub-one-millisecond.

This is critical if you’re trying to make important decisions or control machines in real-time. According to benchmark testing conducted by the GSMA, 5G will slash 4G’s average latency of 50 milliseconds to just one millisecond. For mobile apps, that means faster response times to user input and fewer delays using the app.

Machines will be much closer to talking to each other in the wild, in real-time, as they transmit huge packets of data. This has big implications for things like cloud gaming. Theoretically, you’d no longer need big hardware (like your XBOX or Playstation) to play big games. With 5G you could stream them, making “any time, any place, any device, any network” gaming a reality.

Connected devices. Like, lots of them.

4G supports around 2,000 connected devices per .38 square miles. 5G is expected to support up to 1 million connected devices per .38 square miles.

Yeah. One million. Think about what you could do with a smartwatch app (since the rise of smartwatches will lead to a need for more connected devices per square mile).

For marketers, there is an abundance of opportunity (and lots of potential headaches).

All of this speed and connectivity means that people will be running more devices across more experiences. Once Google launches its cloud gaming service, think about all the people who will be playing from connected TVs, smartphones, and watches, and then transitioning over to YouTube to catch up on sports, TV, or vlogging.

Transitioning between devices already happens, but once 5G hits the scene, it’s going to be a different world. 5G’s speed, latency, and connectivity mean that people will be even more spread out than they already are, consuming all types of media from all kinds of devices. VR and AR will be more prevalent. So will wearable tech, like watches and glasses.

On the one hand, this is really great. You’ll have more information about your customers, simply because they’re consuming more stuff and there’s more data available. You’ll know what they like and what they want, and you’ll be able to serve them better experiences.

But you’ll also need to verify who they are, across all the varied experiences they consume.

It’s already a daunting prospect. ID resolution techniques confirm and analyze identities, to make sure you’re serving ads to real people. The key to ID resolution is first-party data, which is data that’s collected by brands and publishers directly from their customers. Second-party data, meanwhile, is collected by data companies your trust from these brands and publishers to create scale.

Also key: working with a company who sources their data ethically, and is honest with their customers about how they use it.

5G is going to change the game, and offer more chances to consume media than ever before. It’s coming up fast — widely-adopted 5G devices aren’t that far away. Make sure you’re ready and have an established relationship with a partner who understands identity resolution.