tvOS 12.3 is a free update that can be downloaded over the air through the Settings app on the Apple TV by going to System -> Software Update. Apple TV owners who have automatic software updates turned on will be upgraded to tvOS 12.3 automatically.
tvOS 12.3 is the biggest tvOS update Apple has released for quite some time because it introduces an overhauled TV app, which Apple first showed off earlier this year at its March 25 event. The new TV app is similar to the old TV app but it has a refreshed, modern look along with new features.
There are dedicated sections for TV shows, movies, sports, and children's programming, along with access to your iTunes content. There continues to be a "Watch Now" section with an "Up Next" feature for keeping track of the TV shows and movies you're watching, and there's a new machine-learning based "For You" option that surfaces content recommendations based on what you've previously watched.
Apple has included a "Channels" feature, which is a major part of the company's new services push. With Channels, you can subscribe to paid TV content from services like HBO, Showtime, and Starz, and watch that content right within the TV app without having to swap over to a third-party app.
When you subscribe to a service through the TV app, Apple gets a cut of the subscription price and it makes it easier to access third-party content. While Channels are available, the TV app will continue to recommend content that's also only available through third-party apps, so it will work the same way that it did before, but with better recommendations.
The new Apple TV app is available in more than 100 countries starting today, and with Family Sharing, up to six family members are able to share subscriptions to Apple TV channels. Channels content can be watched both online or offline, including HBO content.
In the future, Apple plans to make its new TV+ subscription service available through the TV app, with TV+ offering up access to Apple's original TV shows and movies. The TV app is available on the Apple TV and iOS devices, and in the future, it will expand to the Mac.
Apple has also released new 7.3 software for the third-generation Apple TV models.