Android TV Remote Service is a system app built into Android TV and Google TV. It lets a phone act as the TV's remote over your home Wi-Fi, with navigation, typing and more. Wi-Fi phone remote apps, including Google's Google TV app and The Remote, connect to it. The Remote needs the newer version, Android TV Remote Service v2.
It's the part of your TV that listens for a phone remote
When you pair a phone, this service shows the pairing code on the TV and then accepts commands from the paired phone. Google describes it as the service that lets you use your phone or tablet as a remote. Android TV Remote Service listing
You don't install it: it comes with the TV
It's preinstalled on Android TV and Google TV devices and updates like the TV's other system apps. You won't find it on the home screen. It's listed among system apps in Settings.
The Remote needs Android TV Remote Service v2
The service has had more than one version. The Remote needs Android TV Remote Service v2. If your TV doesn't support it, The Remote can't pair with it. The Remote also works with Google TV devices that support the Android TV Remote Service, including Chromecast with Google TV and Google TV Streamer. Google's streaming-device remote guide
How to see it on your TV
On most Android TV and Google TV models: Settings → Apps → See all apps, then show system apps and look for Android TV Remote Service. Its page shows the installed version. Menu names vary by brand.
Fire TV, Roku and other TVs don't have it
Only Android TV and Google TV include this service. That's why phone remotes built on it don't work with Fire TV, Roku, Samsung (Tizen) or LG (webOS). See does an Android TV remote app work on a Fire TV Stick?
Where The Remote fits
The Remote is a free phone remote for Android TV and Google TV devices with Android TV Remote Service v2. Search YouTube by typing on your phone and the results open on the TV. Share a YouTube link and it plays on the TV. No ads, no account. Your phone needs Android 8.0 or later.