Many people have browser extension ad blockers (which at this point, I don't know how you can browse the internet without one), but some devices do not have this flexibility, namely gaming consoles and smart TVs. When these devices send a request for ad content, or try to 'phone home' with tracking data, the Pi-Hole stops the device in its tracks.
Once you install Pi-Hole, it gives you a nice dashboard as to what is happening on your network. From the below image, you can see ~7.5% of my current network traffic is advertising or tracking. unsurprisingly the most 'chatty' devices are Amazon tablets and Fire TV boxes, they constantly try to send usage data back to Amazon and load ads for the home screen.
With each new release, Pi-Hole adds new features, so it is definitely a project to keep an eye on. Additionally, it is not very resource intensive, so you can add a few more services to the same Raspberry Pi as well. I have mine running Pi-Hole, a Unifi controller, and Datadog agent for network metrics with no issues.
